Update SPIRV libraries (#99)

* Update SPIRV libraries

- Update `spirv-cross`
- Update `spirv-tools`
- Update `glslang`

`spirv-tools` contains a fix for an issue we reported (unnecessary promotions to highp in certain expressions).

* Add SPIRV-Tools dependency to matinfo

third_party/spirv-tools/source/enum_string_mapping.cpp

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "enum_string_mapping.h"
+#include "source/enum_string_mapping.h"
 
 #include <algorithm>
 #include <cassert>
@@ -20,7 +20,7 @@
 #include <string>
 #include <unordered_map>
 
-#include "extensions.h"
+#include "source/extensions.h"
 
 namespace spvtools {