Respect user's pkg-config
--- a/Makefile
+++ b/Makefile
@@ -1,20 +1,10 @@
 # Depends on gmake..
 #
 OS = $(shell uname)
+PKG_CONFIG ?= pkg-config
 
-ifeq ($(OS),FreeBSD)
-	GTK_CONFIG = pkg-config gtk+-2.0
-	INCLUDE = -I/usr/src/sys
-elseif eq ($(OS),NetBSD)
-	GTK_CONFIG = pkg-config gtk+-2.0
-else
-# default to the linux 
-	GTK_CONFIG = pkg-config gtk+-2.0
-endif
-
-
-GTK_CFLAGS = `$(GTK_CONFIG) --cflags` 
-GTK_LIB = `$(GTK_CONFIG) --libs`
+GTK_CFLAGS = $(shell ${PKG_CONFIG} gtk+-2.0 --cflags)
+GTK_LIB = $(shell ${PKG_CONFIG} gtk+-2.0 --libs)
 
 CFLAGS += -Wall -fPIC
 CPPFLAGS += $(GTK_CFLAGS) $(GKRELLM_INCLUDE)