glsl: move the scons build script a level up

It will allow us to remove the duplicate glsl/Makefile.sources.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
diff --git a/src/compiler/SConscript b/src/compiler/SConscript
index 8d71b82..8969d82 100644
--- a/src/compiler/SConscript
+++ b/src/compiler/SConscript
@@ -21,4 +21,4 @@
 )
 Export('compiler')
 
-SConscript('glsl/SConscript')
+SConscript('SConscript.glsl')