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

libc: stop exporting cerror

i386 stopped exporting .cerror in r240152, and likewise for amd64 in
r240178. It is not used by other libraries on any platform, so apply
the same change to the remaining architectures.

Reviewed by: jhibbits, jilles
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D5774

libc: stop exporting curbrk and minbrk in the private namespace

They are not used anywhere else in the base system and are an internal
implementation detail that does not need to be exposed.

Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D5728

Replace a proliferation of buggy MD implementations of modf() with a
working MI one. The MI one only needs to be overridden on machines
with non-IEEE754 arithmetic. (The last supported one was the VAX.)
It can also be overridden if someone comes up with a faster one that
actually passes the regression tests -- but this is harder than it sounds.

Fix whitespace inconsistencies found in homegrown Symbol.maps.

Since nan() is supposed to work the same as strtod("nan(...)", NULL),
my original implementation made both use the same code. Unfortunately,
this meant libm depended on a vendor header at compile time and previously-
unexposed vendor bits in libc at runtime.

Hence, I just wrote my own version of the relevant vendor routine. As it
turns out, mine has a factor of 8 fewer of lines of code, and is a bit more
readable anyway. The strtod() and *scanf() routines still use vendor code.

Reviewed by: bde

Export gdtoa's __ULto{x,Q}_D2A routine in a private namespace so
libm can use it.

Some libc symbol map cleanups.

net: endhostdnsent is named _endhostdnsent and is
private to netdb family of functions.

posix1e: acl_size.c has been never compiled in,
so there's no "acl_size".

rpc: "getnetid" is a static function.

stdtime: "gtime" is #ifdef'ed out in the source.

some symbols are specific only to some architectures,
e.g., ___tls_get_addr is only defined on i386.

__htonl, __htons, __ntohl and __ntohs are no longer
functions, they are now (internal) defines in
<machine/endian.h>.

Submitted by: ru

- Add bits for userland profiling. For sun4u this is compile-tested only.
- Replace magic 14 with PIL_TICK.

Use C comments since we now preprocess these files with CPP.

- Move _Qp_* and __dtoul from FBSDprivate to the list of FBSD_1.0 symbols
as well as add __sparc_utrap_install to FBSD_1.0; these are required by
the SCD libc 64 psABI and thus meant to be officially exported symbols.
- Remove the __fpu_* entries as well as the __sigtramp entry altogether as
these are internal to the libc FPU emulation and the signal trampoline
initialization in sigaction(2) respectively and thus don't need to be
externally visible.
- Add __sparc_utrap_setup to the list of FBSDprivate symbols as it's used
in src/lib/csu/sparc64/crt1.c to initialize the libc FPU emulation (I
think alternatively src/lib/csu/sparc64/crt1.c could be changed to use
__sparc_utrap_install instead, at the expense of increasing the size of
executables a bit).
- Add an entry for the vfork symbol to the FBSD_1 list and entries for it's
associated symbols generated by the RSYSCALL() macro to the FBSDprivate
list. There's some magic in place that automatically generates code for
vfork() if there's no explicit MD code for it so it might make sense to
move these symbols from the MD symbol map files to a MI one.

The last two changes make the libc symbol versioning useable on sparc64.

Ok'ed by: deischen

Add symbol maps and initial symbol version definitions to libc.

Reviewed by: davidxu