testmain is a userland application intended to be built with standard
headers and whatnot, which we broke.
Fix it by having the testmain build clobber cflags, reducing it to just the
set of defines/includes it needs to build.
Discussed with: imp
MFC after: 3 days
OK. We don't really need a bsd.stand.mk, and it was causing a -fPIC
for the toolchain to be added (bogusly) when building on amd64. Pull
all relevant defs back into defs.mk and delete bsd.stand.mk.
This saves about 15-20k on i386 loader and zfsloader which when
combined with Lua give us a lot more stack space in those constrained
environments.
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.
