Find X includes

Index: configure
--- configure.orig
+++ configure
@@ -643,6 +643,7 @@ TK_LIB_SPEC
 TK_LIB_FLAG
 TK_LIB_FILE
 TK_INCLUDE_SPEC
+TK_XINCLUDES
 TK_SRC_DIR
 TK_BIN_DIR
 TK_VERSION