Adding header file for labs().
diff --git a/src/cache/ftcimage.c b/src/cache/ftcimage.c
index 6f15347..294c648 100644
--- a/src/cache/ftcimage.c
+++ b/src/cache/ftcimage.c
@@ -20,6 +20,7 @@
#include <freetype/internal/ftmemory.h>
#include <string.h> /* memcmp() */
+#include <stdlib.h> /* labs() */
/* the FT_Glyph image `glyph node' type */