title: How to use pkg-config in Make
body: <p>I want to compile the simplest GTK program. 
  I can compile it using the command line:</p>
  
  <pre><code>gcc $(pkg-config --cflags --libs gtk+-3.0)  main.c -o main.o
  </code></pre>
  
  <p>However, if I use Make it doesnt work:</p>
  
  <pre><code>CFLAGS=-g -Wall -Wextra $(pkg-config --cflags)
  LDFLAGS=$(pkg-config --libs gtk+-3.0)
  CC=gcc
  
  SOURCES=$(wildcard *.c)
  EXECUTABLES=$(patsubst %.c,%,$(SOURCES))
  
  all: $(EXECUTABLES)
  </code></pre>
  
  <p>It tells me this:</p>
  
  <pre><code>gcc -g -Wall -Wextra    -c -o main.o main.c
  main.c:1:21: fatal error: gtk/gtk.h: No such file or directory
   #include &lt;gtk/gtk.h&gt;
                       ^
  compilation terminated.
  &lt;builtin&gt;: recipe for target 'main.o' failed
  make: *** [main.o] Error 1
  </code></pre>
  
  <p>Where do I stick $(pkg-config --cflags --libs gtk+-3.0) in the Makefile to make it compile?</p>
  
  <p>Thanks very much in advance for your kind help.</p>