kbuild: check if we can link gettext not just compile

cygwin provides the header file but the lib file needs
to be added manually. A generic fix is to check if
we can compile and link a program that uses gettext()
and if it fails fall back to NO_NLS.

International users of cygwin may have to specify
HOST_LOADLIBES := "-lintl" on the make command line.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

scripts/kconfig/Makefile

@@ -143,14 +143,8 @@ clean-files	:= lkc_defs.h qconf.moc .tmp_qtcheck \
 		   .tmp_gtkcheck zconf.tab.c lex.zconf.c zconf.hash.c
 clean-files     += mconf qconf gconf
 
-# Needed for systems without gettext
-KBUILD_HAVE_NLS := $(shell \
-     if echo "\#include <libintl.h>" | $(HOSTCC) $(HOSTCFLAGS) -E - > /dev/null 2>&1 ; \
-     then echo yes ; \
-     else echo no ; fi)
-ifeq ($(KBUILD_HAVE_NLS),no)
-HOSTCFLAGS	+= -DKBUILD_NO_NLS
-endif
+# Add environment specific flags
+HOST_EXTRACFLAGS += $(shell $(CONFIG_SHELL) $(srctree)/$(src)/check.sh $(HOSTCC) $(HOSTCFLAGS))
 
 # generated files seem to need this to find local include files
 HOSTCFLAGS_lex.zconf.o	:= -I$(src)

scripts/kconfig/check.sh

+#!/bin/sh
+# Needed for systems without gettext
+$* -xc -o /dev/null - > /dev/null 2>&1 << EOF
+#include <libintl.h>
+int main()
+{
+	gettext("");
+	return 0;
+}
+EOF
+if [ ! "$?" -eq "0"  ]; then
+	echo -DKBUILD_NO_NLS;
+fi
+