As part of the migration away from obsolete binutils we want to retire
GNU as. Most assembly files used on amd64 have a .S extension and are
assembled with Clang's integrated assembler; rename two files in
stand/i386/btx/lib to .S to use IAS as well.
The generated .text is identical (the entire .o files are not, as Clang
adds debug info).
PR: 205250, 233094
Discussed with: imp
Sponsored by: The FreeBSD Foundation
A foolish consistency is the hobgoblin of little minds, adored by
little statesmen and philosophers and divines. With consistency a
great soul has simply nothing to do. -- Ralph Waldo Emerson
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.
