allow renaming of shader entry point when creating SPIR-V

Use "--source-entrypoint name" on the command line, or the
TShader::setSourceEntryPoint(char*) API.

When the name given to the above interfaces is detected in the
shader source, it will be renamed to the entry point name supplied
to the -e option or the TShader::setEntryPoint() method.

Test/runtests

@@ -45,6 +45,13 @@ $EXE -i -C *.vert *.geom *.frag *.tes* *.comp > singleThread.out
 $EXE -i -C *.vert *.geom *.frag *.tes* *.comp -t > multiThread.out
 diff singleThread.out multiThread.out || HASERROR=1
 
+
+#
+# entry point renaming tests
+#
+$EXE -i -H -V -D -e main_in_spv --source-entrypoint main ../Test/hlsl.entry.rename.frag > $TARGETDIR/hlsl.entry.rename.frag.out
+diff -b $BASEDIR/hlsl.entry.rename.frag.out $TARGETDIR/hlsl.entry.rename.frag.out || HASERROR=1
+
 if [ $HASERROR -eq 0 ]
 then
     echo Tests Succeeded.