Revert "Guard IPC sensitive code everywhere in sources with MOZ_IPC define."

This reverts commit 8a50022eeb8b13f9585241d1f4675828c14c5493.
This also reverts a bunch of other related commits that follow it, including
e3d649f, 5370e8c, 5bffb10, 2f5021c, 727f33b, 6c63a98, and 737a827.

See #9 for details.
[OS/2] Work around gcc command line processing bug that breaks default .exe name.

If a library is specified on the command line with -l and no -o option is given,
the linked executable will get a name like -lthis_library (instead of the name
of the first source file).