clover: Add CL_PROGRAM_BINARY_TYPE support (CL1.2).

clover: Add CL_PROGRAM_BINARY_TYPE support (CL1.2).

v3 [Francisco Jerez]: Loosely based on Serge's v1 of this patch in
   order to avoid CL-specific enums in the clover module binary
   format.  In addition to other changes made in v2: Represent the CL
   program binary type as the section type instead of adding a CL
   API-specific enum, check that the binary types of the input objects
   are valid during clLinkProgram(), pass section type as argument to
   build_module_library() instead of using separate function.

Reviewed-by: Francisco Jerez <currojerez@riseup.net>