Fix build with macports/pkgconfig, silence format string warnings on OS X

Extra space is needed in echo -n "-lncurses ", otherwise if pkg-config outputs a directory after that, it will result in "-lncurses-L/opt/local/lib" (without space).
-Wno-format-security flag is needed on macOS to silence warnings about printf(gettext("message")) constructs.

tools/kconfig/lxdialog/check-lxdialog.sh

@@ -43,7 +43,7 @@ ccflags()
 	fi
 	if [ $(uname -s) == "Darwin" ]; then
 		#OSX doesn't have libintl
-		echo -n "-DKBUILD_NO_NLS"
+		echo -n "-DKBUILD_NO_NLS -Wno-format-security "
 	fi
 }