Change Android FLAGS

Following the discussion in #201 ;).
Tweak Android CFLAGS

Not a fan of the 'use -Os w/ mthumb' thing, which I'd already ammended,
so just do away with that do. Code size isn't our primary concern.
Make sure we always honor LDFLAGS on Android

Because that --fix-cortex-a8 sounds rather ominous..
Minor C/CXXFLAGS mixum
Tweak Android LDFLAGS

That should be overkill, but perhaps the NDK is trying to take care of
the numerous broken projects that call the linker without CFLAGS/CXXFLAGS...