Use bsd.compiler.mk instead of src.opts.mk

- MK_PROFILE is controlled in bsd.opts.mk, which is pulled in via bsd.own.mk,
  which is pulled in via bsd.init.mk . All upstream Makefiles which build off
  of this one use bsd.init.mk.
- COMPILER_{TYPE,VERSION} is set via bsd.compiler.mk .

This reduces the namespace pollution/complexity somewhat.

MFC after:	1 week

lib/libclang_rt/Makefile.inc

@@ -1,6 +1,6 @@
 # $FreeBSD$
 
-.include <src.opts.mk>
+.include <bsd.compiler.mk>
 
 .if ${MACHINE} == "arm"
 .if ${MACHINE_ARCH:Marmv[67]*} != "" && ${CPUTYPE:M*soft*} == ""