Use unsigned for quantities that can be < 0.

--HG--
branch : HEAD

lib/zip_open.c

diff --git a/lib/zip_open.c b/lib/zip_open.c
index e8030fe..81bb5e2 100644
--- a/lib/zip_open.c
+++ b/lib/zip_open.c
@@ -182,7 +182,7 @@
     struct zip_cdir *cd;
     const unsigned char *cdp;
     const unsigned char **bufp;
-    zip_uint32_t comlen;
+    zip_int32_t comlen;
     int i;
     zip_uint32_t left;