xdpyinfo.c:173:17: warning: implicit conversion changes signedness: 'int' to
      'size_t' (aka 'unsigned long') [-Wsign-conversion]
        qsort(extlist, n, sizeof(char *), StrCmp);
        ~~~~~          ^
xdpyinfo.c:183:26: warning: implicit conversion changes signedness: 'int' to
      'unsigned long' [-Wsign-conversion]
            qe_cookies = calloc(n, sizeof(xcb_query_extension_cookie_t));
                         ~~~~~~ ^
xdpyinfo.c:195:12: warning: implicit conversion loses integer precision:
      'unsigned long' to 'uint16_t' (aka 'unsigned short') [-Wconversion]
                                                     strlen(extlist[i]),
                                                     ^~~~~~~~~~~~~~~~~~
xdpyinfo.c:1382:51: warning: implicit conversion loses integer precision:
      'unsigned long' to 'int' [-Wshorten-64-to-32]
        int extlen = strlen(known_extensions[i].extname) + 1;
            ~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>