OS X compiler flags

While reading Apple documentation, I noticed that gcc has an -Os
option that performs most of the -O2 optimizations, leaves out those
that increase code size, and performs additional code size
optimizations. Also, Apple documentation said the -dead_strip linker
flag we use should be combined with -gfull for maximum effectiveness.

Should we try the "-Os -gfull" flags on tinderbox?

Results with a static build:

   bytes file
----------------------------

-O

10557580 firefox-bin
   14992 libxpcom.dylib
  613384 libmozjs.dylib
  507700 libxpcom_core.dylib

----------------------------

-O2 -g

11163428 firefox-bin
   14992 libxpcom.dylib
  658468 libmozjs.dylib
  548688 libxpcom_core.dylib

----------------------------

-Os -gfull

 9666924 firefox-bin
   14992 libxpcom.dylib
  605220 libmozjs.dylib
  484720 libxpcom_core.dylib



.mozconfig file:
----------------------------
. $topsrcdir/browser/config/mozconfig
mk_add_options MOZ_OBJDIR=@TOPSRCDIR@/ff-opt-static
ac_add_options --enable-optimize="-Os -gfull"
ac_add_options --disable-debug
ac_add_options --enable-static
ac_add_options --disable-shared
ac_add_options --disable-libxul
ac_add_options --disable-tests