Changed compiler for iOS to GCC 4.2 (from Apple LLVM) due to terrible bug MOSYNC-2827

... preffered compiler to GCC 4.2. Because of the change in compiler, a piece of conditional code was added in intlibs/bluetooth/connection.cpp to correctly define a global that was originally only declared as extern (but Apple's compiler didn't mind).

This was the worst bug that I have seen in my entire life.