"struct spv_context_t" misses a typedef for C compilation

[yoanlcq]

Including libspirv.h in a C project causes an error at this line :
https://github.com/KhronosGroup/SPIRV-Tools/blob/master/include/spirv-tools/libspirv.h#L344
because spv_context_t isn't a known type, but struct spv_context_t is.

Since libspirv is intended as a C API, this should be fixed by adding
typedef struct spv_context_t spv_context_t; just here :
https://github.com/KhronosGroup/SPIRV-Tools/blob/master/include/spirv-tools/libspirv.h#L334

[dekimir]

Will fix, but libspirv.h is currently far from being C friendly. It has several other non-C constructs, such as bool and namespace in OpenCL.std.h.

[dekimir]

Fixed via c31a319.