Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

The register_printf_render_std() function expects regular string.
Change argument type from 'const unsigned char *' to 'const char *'.

MFC after: 2 weeks

- Use an initializer macro to initialize fields in 'fake' FILE objects used
by *sprintf(), etc.
- Explicitly initialize _fl_mutex to PTHREAD_MUTEX_INITIALIZER for all FILE
objects. This is currently a nop on FreeBSD, but is import for other
platforms (or in the future) where PTHREAD_MUTEX_INITIALIZER is not simply
zero.

PR: threads/141198
Reported by: Jeremy Huddleston @ Apple
MFC after: 2 weeks

Expose FILE's internals to the world again in all their glory. Restore
all the previous inline optimizations as well. FILE is back to using
__mbstate_t, struct pthread *, and struct pthread_mutex *.

Next round of stdio changes: Remove all inlining of stdio operations and
move the definition of the type backing FILE (struct __sFILE) into an
internal header.
- Remove macros to inline certain operations from stdio.h. Applications
will now always call the functions instead.
- Move the various foo_unlocked() functions from unlocked.c into foo.c.
This lets some of the inlining macros (e.g. __sfeof()) move into
foo.c.
- Update a few comments.
- struct __sFILE can now go back to using mbstate_t, pthread_t, and
pthread_mutex_t instead of knowing about their private, backing types.

MFC after: 1 month
Reviewed by: kan

Next stage of stdio cleanup: Retire __sFILEX and merge the fields back into
__sFILE. This was supposed to be done in 6.0. Some notes:
- Where possible I restored the various lines to their pre-__sFILEX state.
- Retire INITEXTRA() and just initialize the wchar bits (orientation and
mbstate) explicitly instead. The various places that used INITEXTRA
didn't need the locking fields or _up initialized. (Some places needed
_up to exist and not be off the end of a NULL or garbage pointer, but
they didn't require it to be initialized to a specific value.)
- For now, stdio.h "knows" that pthread_t is a 'struct pthread *' to
avoid namespace pollution of including all the pthread types in stdio.h.
Once we remove all the inlines and make __sFILE private it can go back
to using pthread_t, etc.
- This does not remove any of the inlines currently and does not change
any of the public ABI of 'FILE'.

MFC after: 1 month
Reviewed by: peter

Revert the rev. 1.4, it causes breakage on most arches except i386.

Remove the const qualifier from ap argument for __v2printf, that induced
that breakage, and seems to be the real reason for bad code. ap is modified
inside the __v2printf body by va_arg macro.

Pointy hat to: kib
Approved by: pjd (mentor)

Workaround for (what seems to be) compiler error for gcc 3.4.6. On
i386 with default optimization level (-O2), va_list pointer ap in the
__v2printf function is advanced before the use. That cause argument
shift and garbage instead last argument in printf-family when xprintf is
activated.

The nsswitch is easy victim of the bug.

Reviewed by: kan
Approved by: kan (mentor)
MFC after: 1 week

Add missing #if's for NO_FLOATING_POINT

Make the %V{is} extension handle a NULL pointer like %s does: output "(null)"

Add %M{essage} extension which prints an errno value as the
corresponding string if possible or numerically otherwise.

It is not currently possible to do the syslog(3) like %m extension
because errno would need to get capatured on entry to the first
function in the printf family, so %M requires you to supply errno
as an argument.

Add %Q{uote} extension which will print a string in double quotes with
appropriate back-slash escapes (only) if necessary.

Add an extensible version of our *printf(3) implementation to libc
on probationary terms: it may go away again if it transpires it is
a bad idea.

This extensible printf version will only be used if either
environment variable USE_XPRINTF is defined
or
one of the extension functions are called.
or
the global variable __use_xprintf is set greater than zero.

In all other cases our traditional printf implementation will
be used.

The extensible version is slower than the default printf, mostly
because less opportunity for combining I/O operation exists when
faced with extensions. The default printf on the other hand
is a bad case of spaghetti code.

The extension API has a GLIBC compatible part and a FreeBSD version
of same. The FreeBSD version exists because the GLIBC version may
run afoul of our FILE * locking in multithreaded programs and it
even further eliminate the opportunities for combining I/O operations.

Include three demo extensions which can be enabled if desired: time
(%T), hexdump (%H) and strvis (%V).

%T can format time_t (%T), struct timeval (%lT) and struct timespec (%llT)
in one of two human readable duration formats:
"%.3llT" -> "20349.245"
"%#.3llT" -> "5h39m9.245"

%H will hexdump a sequence of bytes and takes a pointer and a length
argument. The width specifies number of bytes per line.
"%4H" -> "65 72 20 65"
"%+4H" -> "0000 65 72 20 65"
"%#4H" -> "65 72 20 65 |er e|"
"%+#4H" -> "0000 65 72 20 65 |er e|"

%V will dump a string in strvis format.
"%V" -> "Hello\tWor\377ld" (C-style)
"%0V" -> "Hello\011Wor\377ld" (octal)
"%+V" -> "Hello%09Wor%FFld" (http-style)

Tests, comments, bugreports etc are most welcome.