Fix compile time warnings to make it possible to build package with -Werror.

main.c: In function 'random_seed':
main.c:100:3: warning: ignoring return value of 'read', declared with attribute warn_unused_result [-Wunused-result]
   read (fd, &seed, sizeof(seed));
   ^

If required number of seed bytes can not be read from the random device, fall
back to using using predictable, but frequently changing seed.  The macchanger
does not require high quality randomness, and the predictable seed method is
already fallback for cases when no random device is available.

mac.c: In function 'mc_mac_read_string':
mac.c:116:3: error: format '%lu' expects argument of type 'long unsigned int', but argument 4 has type 'size_t' [-Werror=format=]
   fprintf (stderr, "[ERROR] Incorrect format: MAC length should be 17. %s(%lu)\n", string, strlen(string));
   ^

Fix format string to use %z.  Required for 32bit architectures.

diff -pruN macchanger-1.7.0.orig/src/main.c macchanger-1.7.0/src/main.c
--- macchanger-1.7.0.orig/src/main.c	2014-07-04 09:44:29.505142598 +0200
+++ macchanger-1.7.0/src/main.c	2014-07-04 10:16:32.238186470 +0200
@@ -93,13 +93,17 @@ random_seed (void)
 	int            fd;
 	struct timeval tv;
 	unsigned int   seed;
+	int            have_seed = 0;
 
 	if ((fd = open("/dev/urandom", O_RDONLY)) >= 0 ||
 	    (fd = open("/dev/random", O_RDONLY)) >= 0)
 	{
-		read (fd, &seed, sizeof(seed));
+		have_seed = ( read (fd, &seed, sizeof(seed)) == sizeof(seed) );
 		close (fd);
-	} else {
+	}
+	
+	/* Use predictable non-constant seed as fallback */
+	if (!have_seed) {
 		gettimeofday (&tv, NULL);
 		seed = (getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec;
 	}
diff -pruN macchanger-1.7.0.orig/src/mac.c macchanger-1.7.0/src/mac.c
--- macchanger-1.7.0.orig/src/mac.c	2013-04-18 07:27:17.000000000 +0200
+++ macchanger-1.7.0/src/mac.c	2014-07-04 10:37:13.074214783 +0200
@@ -113,7 +113,7 @@ mc_mac_read_string (mac_t *mac, char *st
 
 	/* Check the format */
 	if (strlen(string) != 17) {
-		fprintf (stderr, "[ERROR] Incorrect format: MAC length should be 17. %s(%lu)\n", string, strlen(string));
+		fprintf (stderr, "[ERROR] Incorrect format: MAC length should be 17. %s(%zu)\n", string, strlen(string));
 		return -1;
 	}