Implement GL_EXT_terminate_invocation (#2454)

* Implement GL_EXT_terminate_invocation.

* terminateInvocation: declare the SPV extension

* Update test results for spirv-tools and bison version bumps

Co-authored-by: John Kessenich <cepheus@frii.com>
diff --git a/SPIRV/spvIR.h b/SPIRV/spvIR.h
index 868b9bf..486e80d 100644
--- a/SPIRV/spvIR.h
+++ b/SPIRV/spvIR.h
@@ -263,6 +263,7 @@
         case OpBranchConditional:
         case OpSwitch:
         case OpKill:
+        case OpTerminateInvocation:
         case OpReturn:
         case OpReturnValue:
         case OpUnreachable: