Correct error in comment for gz_make().

gzread.c

@@ -298,7 +298,7 @@ local int gz_decomp(state)
    Data is either copied from the input file or decompressed from the input
    file depending on state->how.  If state->how is LOOK, then a gzip header is
    looked for (and skipped if found) to discern whether to copy or decompress.
-   Returns -1 on error, otherwise 0.  gz_make() will leave state->have as COPY
+   Returns -1 on error, otherwise 0.  gz_make() will leave state->how as COPY
    or GZIP unless the end of the input file has been reached and all data has
    been processed.  */
 local int gz_make(state)