Fix gcc-uClibc.h dependancies

extra/gcc-uClibc/Makefile

@@ -14,7 +14,7 @@ GCCINCDIR:= ${shell $(CC) -print-search-dirs | sed -ne "s/install: \(.*\)/\1incl
 
 all: gcc-uClibc ld-uClibc
 
-gcc-uClibc.h:
+gcc-uClibc.h: Makefile $(TOPDIR)/.config
 	@echo "/* this file was autogenerated by make */" > gcc-uClibc.h
 	@echo "#define UCLIBC_TARGET_PREFIX " \"$(TARGET_PREFIX)\" >> gcc-uClibc.h
 	@echo "#define UCLIBC_DEVEL_PREFIX " \"$(DEVEL_PREFIX)\" >> gcc-uClibc.h