Cygwin: resolver: Targets in SRV DNS responses may not be compressed

RFC2782 clearly says so yet it's a common misconception to perform the
compression in the violation of the standard.  This patch fixes that

winsup/cygwin/libc/minires-os-if.c

@@ -159,6 +159,7 @@ static unsigned char * write_record(unsigned char * ptr, PDNS_RECORD rr,
       PUTSHORT(rr->Data.SRV.wWeight, ptr);
       PUTSHORT(rr->Data.SRV.wPort, ptr);
     }
+    dnptrs = 0;  /* compression not allowed */
     PUTDOMAIN(rr->Data.SRV.pNameTarget, ptr);
     break;
   default: