Remove residual blank line at start of Makefile

This is a residual of the $FreeBSD$ removal.

MFC After: 3 days (though I'll just run the command on the branches)
Sponsored by: Netflix

Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Merge ^/head r340918 through r341763.

btx: rename .s files to .S to use Clang IAS

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 wi

btx: rename .s files to .S to use Clang IAS

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

show more ...

Centralize several variables.

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 repeti

Centralize several variables.

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.

show more ...

Merge ^/head r325663 through r325841.

Move sys/boot to stand. Fix all references to new location

Sponsored by: Netflix