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>
