moved all lower_* header into new lowering.h

[r14256]

ir/be/ia32/ia32_intrinsics.c

@@ -33,8 +33,7 @@
 #include "irnode_t.h"
 #include "ircons.h"
 #include "irprog_t.h"
-#include "lower_intrinsics.h"
-#include "lower_dw.h"
+#include "lowering.h"
 #include "array.h"
 
 #include "ia32_new_nodes.h"