kill HAVE_FORKEXEC

Bug: 18317407
Change-Id: I4eecb3c9d745e3dabfc46fa595aac7f94f6d93e3
Add LOCAL_MULTILIB := both to Darwin libbacktrace.

This was previously set for libbacktrace_libc++, but apparently never
was for libbacktrace.

Change-Id: I85dc44b356710c6367f5cea3bc0a4d6c817ca202
Merge "Add LOCAL_MULTILIB := both to Darwin libbacktrace."
Merge "kill HAVE_FORKEXEC"
Fix a trivial typo.

Clang compiler gave a correct warning on this mismatch of
names in #ifndef and #define.

Change-Id: I360f0c40ee98162093dde8f9815a02a54e5b2cb7
Merge "Fix a trivial typo."