MK_CTF, MK_SSP, MK_PROFILE, NO_PIC, and INTERNALLIB are always the
same, so set them in defs.mk. MAN= is common, so set it here too.
This removes a lot of boring repetition from the Makefiles that added
almost no value.
Only define the CFLAGS we need.
SSP_CFLAGS is now defined globally, no need to define it here.
Define -D_STANDALONE globally for src/stand builds.
Sponsored by: Netflix
Remove the now-useless dependency on ufsread.c. In some cases, it was
on the wrong file. But in all cases, we now automatically generate
.depend files, so we don't need it explicitly.
Sponsored by: Netflix
simd / no float stuff is centeralized here. Also centralise
-ffreestanding since it is specified everywhere.
This, along with a change to share/mk/bsd.cpu.mk to include -mno-avx2
in CFLAGS_NO_SIMD should fix building for newer machines (eg with
CPUTYPE=haswell) where clang was generating avx2 instructions.
Sponsored by: Netflix
