GLSL: Promote HLSL entry-point renaming code to be used by GLSL as well.

Fixes #1045.
diff --git a/Test/runtests b/Test/runtests
index f0da75f..3cceb43 100755
--- a/Test/runtests
+++ b/Test/runtests
@@ -157,6 +157,16 @@
 $EXE -G100                   spv.targetOpenGL.vert || HASERROR=1
 
 #
+# Testing GLSL entry point rename
+#
+$EXE -H -e foo --source-entrypoint main glsl.entryPointRename.vert > $TARGETDIR/glsl.entryPointRename.vert.out
+diff -b $BASEDIR/glsl.entryPointRename.vert.out $TARGETDIR/glsl.entryPointRename.vert.out || HASERROR=1
+$EXE -H -e foo --source-entrypoint bar glsl.entryPointRename.vert > $TARGETDIR/glsl.entryPointRename.vert.bad.out
+diff -b $BASEDIR/glsl.entryPointRename.vert.bad.out $TARGETDIR/glsl.entryPointRename.vert.bad.out || HASERROR=1
+$EXE -H -e foo --source-entrypoint main glsl.entryPointRename2.vert > $TARGETDIR/glsl.entryPointRename2.vert.out
+diff -b $BASEDIR/glsl.entryPointRename2.vert.out $TARGETDIR/glsl.entryPointRename2.vert.out || HASERROR=1
+
+#
 # Final checking
 #
 if [ $HASERROR -eq 0 ]