Do not initialize unsigned with -1 in compress.c uncompr.c.

Sun compiler complained.  Use (unsigned)0 - 1 instead.

compress.c

@@ -28,7 +28,7 @@ int ZEXPORT compress2 (dest, destLen, source, sourceLen, level)
 {
     z_stream stream;
     int err;
-    const uInt max = -1;
+    const uInt max = (uInt)0 - 1;
     uLong left;
 
     left = *destLen;

uncompr.c

@@ -30,7 +30,7 @@ int ZEXPORT uncompress (dest, destLen, source, sourceLen)
 {
     z_stream stream;
     int err;
-    const uInt max = -1;
+    const uInt max = (uInt)0 - 1;
     uLong left;
     Byte buf[1];    /* for detection of incomplete stream when *destLen == 0 */