glsl: Include main/core.h.

Make glsl include only main/core.h from core mesa.
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 38d19c4..c5c8c9c 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -72,10 +72,7 @@
 #include <talloc.h>
 }
 
-#include "main/compiler.h"
-#include "main/mtypes.h"
-#include "main/macros.h"
-#include "main/shaderobj.h"
+#include "main/core.h"
 #include "glsl_symbol_table.h"
 #include "ir.h"
 #include "program.h"