fontsrv: only build when the pieces are there

INSTALL

@@ -89,6 +89,21 @@ if [ `uname` = Darwin ]; then
 	rm -f ./a.out
 fi
 
+if [ `uname` != Darwin ]; then
+	# Determine whether fontsrv X11 files are available.
+	rm -f a.out
+	gcc -o a.out -c -Iinclude -I/usr/include -I/usr/include/freetype2 src/cmd/fontsrv/x11.c >/dev/null 2>&1
+	if [ -f a.out ]; then
+		echo "	fontsrv dependencies found."
+		echo "FONTSRV=fontsrv" >>$PLAN9/config
+	else
+		echo "	fontsrv dependencies not found."
+		echo "FONTSRV=" >>$PLAN9/config
+		rm -f bin/fontsrv
+	fi
+	rm -f a.out
+fi
+
 if [ -f LOCAL.config ]; then
 	echo Using LOCAL.config options:
 	sed 's/^/	/' LOCAL.config