IOPort/Unix: Fix missing init assignment of lineTerminator to _POSIX_VDISABLE

Had a == instead of =, so the init was a no-op. Found by llvm clang
compiler.
Adapt to OSX 10.9 Mavericks and 10.9-SDK, rebuild all OSX mex files.

Change base SDK from 10.6 to 10.9, as 10.6 and 10.7 SDK's are no longer
available on the 10.9 build system. Change compiler to llvm-gcc from
llgv-gcc-4.2.
Make modifications to fix as many compile time warnings as possible.
Rebuild all Matlab and Octave mex files for 64-Bit OSX.

All mex files except Screen build without warnings. Remaining warnings
at this point:
- GStreamer deprecated function warnings. Those are on all platforms ->
unrelated.
- CGDisplayBitsPerPixel implicit declaration and CGDisplayBeamposition
implicit declaration. These have been removed from 10.9 SDK but code
still magically works.
- ATSUxxx function implicit declaration warnings in SCREENDrawText.
These have been removed from 64-Bit SDK headers but still magically
work.
-> This could only be fixed by rewriting the ATSUI text renderer into a
CoreText text renderer, and changing CGxxx api. Keep it for now as is,
as long as it works.
-> CGDisplayBeamposition() is a candidate for removal. It has limited
use on 10.6 (Only NVidia gpu's supported), even more limited use on
10.7 (slight inaccuracies, PsychtoolboxKernelDriver is always the
better option), almost no use on 10.8 (only works on VGA-CRT monitors)
and is completely dysfunctional on 10.9 - The function only returns the
-1 "feature unsupported" status code and triggers our fallbacks. All in
all the function is almost useless and mostly a maintenance burden at
this point.

-> This set of Octave mex files is compatible with the Octave-3.7.7+
GUI prototype, useful for testing with Octave GUI on OSX.