Fix parsing of unknown directives in resolv.conf

Only call eatline() to skip to the next line if we're not
already at the end of a line when parsing an unknown directive.
We were accidentally skipping the next line when there was only
a single unknown directive on the current line.

(cherry picked from commit eb78ad2080)

lib/irs/resconf.c

@@ -578,9 +578,11 @@ irs_resconf_load(isc_mem_t *mctx, const char *filename, irs_resconf_t **confp) {
 			} else {
 				/* unrecognised word. Ignore entire line */
 				rval = ISC_R_SUCCESS;
-				stopchar = eatline(fp);
-				if (stopchar == EOF) {
-					break;
+				if (stopchar != '\n') {
+					stopchar = eatline(fp);
+					if (stopchar == EOF) {
+						break;
+					}
 				}
 			}
 			if (ret == ISC_R_SUCCESS && rval != ISC_R_SUCCESS) {