Fixes compiler warning
Fixes compiler warning

src/genlib/net/http/httpparser.c: In function ‘parser_parse_headers’:
src/genlib/net/http/httpparser.c:1534:19: warning: assignment discards
‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
     hdr_value.buf = "\0";
                   ^

mrjimenez/pupnp,mrjimenez/pupnp,mrjimenez/pupnp,mrjimenez/pupnp