glsl/ast/ir: Add 64-bit integer constant support

glsl/ast/ir: Add 64-bit integer constant support

This adds support for 64-bit integer constants to the parser,
ast and ir.

v2: fix a few issues found in testing.

v3: Add missing ir_constant copy contructor support.

v4: Use PRIu64 and PRId64 in printfs in glsl_parser_extras.cpp.
Suggested by Nicolai.  Rebase on Marek's linalloc changes.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com> [v2]
Reviewed-by: Matt Turner <mattst88@gmail.com> [v3]
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>