Basic: fix __{,U}INTPTR_TYPE__ on ARM

Darwin and OpenBSD are the only platforms which use `long int` for
`__INTPTR_TYPE__`.  The other platforms use `int` in 32-bit, and `long
int` on 64-bit (except for VMS and Windows which are LLP64).  Adjust the
type definitions to match the platform definitions.  We now generate the
same definition as GCC on all the targets.

llvm-svn: 316046