Fix bug that accepted invalid zlib header when windowBits is zero.

When windowBits is zero, the size of the sliding window comes from
the zlib header.  The allowed values of the four-bit field are
0..7, but when windowBits is zero, values greater than 7 are
permitted and acted upon, resulting in large, mostly unused memory
allocations.  This fix rejects such invalid zlib headers.

inflate.c

@@ -674,7 +674,7 @@ int flush;
             len = BITS(4) + 8;
             if (state->wbits == 0)
                 state->wbits = len;
-            else if (len > state->wbits) {
+            if (len > 15 || len > state->wbits) {
                 strm->msg = (char *)"invalid window size";
                 state->mode = BAD;
                 break;