Fix (and test) more Clang 14 compiler warnings

-Woverlength-strings, -Wshift-negative-value, -Wsign-compare

cjpeg.c

@@ -361,7 +361,8 @@ parse_switches(j_compress_ptr cinfo, int argc, char **argv,
       if (!printed_version) {
         fprintf(stderr, "%s version %s (build %s)\n",
                 PACKAGE_NAME, VERSION, BUILD);
-        fprintf(stderr, "%s\n\n", JCOPYRIGHT);
+        fprintf(stderr, JCOPYRIGHT1);
+        fprintf(stderr, JCOPYRIGHT2 "\n");
         fprintf(stderr, "Emulating The Independent JPEG Group's software, version %s\n\n",
                 JVERSION);
         printed_version = TRUE;