Changed Makefile to use pkg-config to find libraries.

Makefile

@@ -1,7 +1,5 @@
-output: dwmblocks.o
-	gcc dwmblocks.o -lX11 -o dwmblocks
-dwmblocks.o: dwmblocks.c blocks.h
-	gcc -c -lX11 dwmblocks.c 
+output: dwmblocks.c blocks.h
+	cc `pkg-config --cflags x11` `pkg-config --libs x11` dwmblocks.c -o dwmblocks
 clean:
 	rm -f *.o *.gch dwmblocks
 install: output