fix compiler warnings

Include all nessecary headers, use the correct format strings and don't
redefine _GNU_SOURCE.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>

dmapi/src/suite2/src/mmap.c

@@ -41,6 +41,7 @@
 #include <string.h>
 #include <errno.h>
 #include <getopt.h>
+#include <stdlib.h>
 
 
 char * Progname;