This is the third and final part of the __builtin_flush_icache patch.
It replaces the hard coded library call to cacheflush() in the MIPS
ffi_prep_closure_loc with a call to __builtin_flush_icache();

For targets that support user-space i-cache flushing (mips32r2), this
will eliminate a system call from the ffi closure preparation path.
On all other targets the generated code is the same as before.

Bootstrapped and tested on x86_64-unknown-linux-gnu all default
languages with no regressions.

Also tested on:
 x86_64 cross to mipsel-linux --with-arch=mips32
 i686   cross to mipsel-linux --with-arch=mips32r2

with no regressions.

OK to commit?

libffi/:
2007-06-30  David Daney  <ddaney@avtrex.com>

    * src/mips/ffi.c: Don't include sys/cachectl.h.
    (ffi_prep_closure_loc): Use __builtin_flush_icache() instead of
    cacheflush().