libmudflap/mf-hooks2.c portability breakage

[law@redhat.com]

In message <3F267DC2.2EB6899E@eyal.emu.id.au>, Eyal Lebedinsky writes:
 >Gerald Pfeifer wrote:
 >> 
 >> FreeBSD fails to bootstrap tree-ssa branch, because libmudflap/mf-hooks2.c
 >> contains
 >[trimmed]
 >
 >This was expected, as mf-hooks2.c was only tested on Linux so far. Well,
 >at least my part (after /* EL start */). The set of #defines that
 >followes that comment will need to become system dependent, and
 >maybe even library version dependent. I assume the earlier portion
 >of this source file will also require such adjustments.
 >
 >It is best, at some point soon, to add more feature macros and
 >set these all up-front. One such macro will specify if we want to
 >#define _POSIX_SOURCE. This is a cleaner solution for a generic
 >feature.
 >
 >We should be able to use autoconf to set these too, but for now,
 >I think the posted patch looks reasonable.
Shouldn't all that stuff be auto-conf'd?

jeff