Remove KernelArgInfo::pointeeTypeName

It's redundant now that WebCLTypes::reduceType produces a clean enough
pointer type, and we've got rid of the silly cl_mem host types in the
JSON header
Report uchar, ... instead of unsigned char, ... for kernel args

This is consistent with OpenCL 1.2+ clGetKernelArgInfo semantics
Bare minimum C API for libwclv

Includes running the validator with specified input, determining
outcome, getting validated source and freeing resources

JSON header printing is disabled until there is C API for kernel info

Errors are still output on the library side
Don't limit reported errors count at clang level

Do that in the CLI binary once it handles error printing