- Don't define NO_IMPLICIT_EXTERN_C here. It is already the default
(defined in i386/bsd.h).
- Don't lose the fixed comment about FUNCTION_PROFILER.
- Don't lose the define of NO_PROFILE_DATA.
Replace the unused define of COMMENT_BEGIN by the less-unused define
of ASM_COMMENT_START. COMMENT_BEGIN was only defined in i386-specific
files and was not used in any part of gcc-2.6.3. ASM_COMMENT_START
is defined for several targets and is used for stuff that we don't
support (dwarf).