Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

MFC r257532 (by adrian):

Fix this build for clang.

MFC r259730:

To avoid having to explicitly test COMPILER_TYPE for setting
clang-specific or gcc-specific flags, introduce the following new
variables for use in Makefiles:

CFLAGS.clang
CFLAGS.gcc
CXXFLAGS.clang
CXXFLAGS.gcc

In bsd.sys.mk, these get appended to the regular CFLAGS or CXXFLAGS for
the right compiler.

MFC r259913:

For libstand and sys/boot, split off gcc-only flags into CFLAGS.gcc.

MFC r259927:

Fix pc98 build, by also forcing COMPILER_TYPE in sys/boot/pc98/boot2's
Makefile.

Pointy hat to: dim

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Use MK_SSP=no after including bsd.own.mk to disable SSP instead of user-knob
WITH[OUT]_SSP to avoid hitting an error if user has WITH_SSP in their
make.conf. Ports now use this knob.

make[7]: "/usr/src/share/mk/bsd.own.mk" line 466: WITH_SSP and
WITHOUT_SSP can't both be set.

This is similar to previous cleanup done in r188895

Approved by: bapt
Reviewed by: jlh (earlier version)
Approved by: re (marius)
MFC after: 1 week

Move the 64-bit _setjmp to lib/libstand.

MFV: Update zlib to 1.2.7.

(x86 assembler optimization disabled for now because it
requires the new .cfi_* directives that is not supported
by base system binutils).

MFC after: 1 week

Merge index() and strchr() together.

As I looked through the C library, I noticed the FreeBSD MIPS port has a
hand-written version of index(). This is nice, if it weren't for the
fact that most applications call strchr() instead.

Also, on the other architectures index() and strchr() are identical,
meaning we have two identical pieces of code in the C library and
statically linked applications.

Solve this by naming the actual file strchr.[cS] and let it use
__strong_reference()/STRONG_ALIAS() to provide the index() routine. Do
the same for rindex()/strrchr().

This seems to make the C libraries and static binaries slightly smaller,
but this reduction in size seems negligible.

Add a version of the FreeBSD bootloader which can run in userland, packaged
as a shared library. This is intended to be used by BHyVe to load FreeBSD
kernels into new virtual machines.