Add missing comma from license-checker.cfg

Fixes license checker presubmit.

Author: ben-clayton

license-checker.cfg

@@ -21,7 +21,7 @@
                 "glslang/OSDependent/Web/glslang.*.js",
 
                 "glslang/MachineIndependent/glslang_tab.cpp",
-                "glslang/MachineIndependent/glslang_tab.cpp.h"
+                "glslang/MachineIndependent/glslang_tab.cpp.h",
 
                 "glslang/MachineIndependent/glslang_angle_tab.cpp",
                 "glslang/MachineIndependent/glslang_angle_tab.cpp.h"