Fix misc. issues reported by Coverity.

Some uninitialized values, a possible null pointer dereference, and
time-of-check-time-of-use on reading random seed file.

src/util.cc

@@ -652,16 +652,8 @@ void hmac_md5(size_t size, const unsigned char* bytes, unsigned char digest[16])
 static bool read_random_seeds(const char* read_file, uint32* seed,
 				uint32* buf, int bufsiz)
 	{
-	struct stat st;
 	FILE* f = 0;
 
-	if ( stat(read_file, &st) < 0 )
-		{
-		reporter->Warning("Seed file '%s' does not exist: %s",
-				read_file, strerror(errno));
-		return false;
-		}
-
 	if ( ! (f = fopen(read_file, "r")) )
 		{
 		reporter->Warning("Could not open seed file '%s': %s",