Add support for language-specific address spaces. On top of that,

Add support for language-specific address spaces.  On top of that,
add support for the OpenCL __private, __local, __constant and
__global address spaces, as well as the __read_only, _read_write and
__write_only image access specifiers.  Patch originally by ARM;
language-specific address space support by myself.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@127915 91177308-0d34-0410-b5e6-96231b3b80d8