Update Makefile

Makefile

@@ -1,14 +1,23 @@
-CFLAGS=-g -Wall
-INCS=-I/usr/X11R6/include
-LIBS=-L/usr/X11R6/lib -lX11
+.POSIX:
 
-all: clean xpick
+PREFIX ?= /usr/local
+PKG_CONFIG = pkg-config
+
+CFLAGS = -Wall `$(PKG_CONFIG) --cflags x11`
+LDFLAGS = `$(PKG_CONFIG) --libs x11`
+
+all: xpick
 
 xpick:
-	$(CC) $(CFLAGS) $(INCS) $(LIBS) -o ${@} xpick.c
+	$(CC) $(CFLAGS) -o ${@} xpick.c $(LDFLAGS)
 
 clean:
 	rm -f xpick
 
 install: xpick
-	install -m755 xpick /usr/local/bin/xpick
+	install -m755 xpick $(DESTDIR)$(PREFIX)/bin/xpick
+
+uninstall:
+	rm -f $(DESTDIR)$(PREFIX)/bin/xpick
+
+.PHONY: all clean install uninstall