Import gx, PadClamp, rest of mtx, TRK 2.6 and MSL (#525)

* Match mtx and Padclamp.c

* Match the rest of GX

* Import TRK 2.6

* Import MSL headers and files

* Merge some MSL headers into ours

src/MSL_C.PPCEABI.bare.H/errno.c

@@ -0,0 +1,3 @@
+#include "PowerPC_EABI_Support/Msl/MSL_C/MSL_Common/errno.h"
+
+int errno;