This commit bulk updates all '.h', '.cl', '.inc', and '.cpp' files to
add any missing license headers.
The remaining files are generally CMake, SOURCES, scripts, markdown,
etc.
There are still some '.ll' files which may benefit from a license
header. I can't find an example of an LLVM IR file with a license header
in the rest of LLVM, but unlike most other (sub)projects, libclc has
examples of LLVM IR as source files, compiled and built into the
library.
This commit moves over the OpenCL clz, hadd, mad24, mad_hi, mul24,
mul_hi, popcount, rhadd, and upsample builtins to the CLC library.
This commit also optimizes the vector forms of the mul_hi and upsample
builtins to consistently remain in vector types, instead of recursively
splitting vectors down to the scalar form.
The OpenCL mad_hi builtin wasn't previously publicly available from the
CLC libraries, as it was hash-defined to mul_hi in the header files.
That issue has been fixed, and mad_hi is now exposed.
The custom AMD implementation/workaround for popcount has been removed
as it was only required for clang < 7.
There are still two integer functions which haven't been moved over. The
OpenCL mad_sat builtin uses many of the other integer builtins, and
would benefit from optimization for vector types. That can take place in
a follow-up commit. The rotate builtin could similarly use some more
dedicated focus, potentially using clang builtins.
