printers.c: Save strings file path when PPD cache is not out of date

Applying Mike's requested changes and mention the fix in CHANGES.

CHANGES.md

@@ -15,6 +15,9 @@ Changes in CUPS v2.4.3 (TBA)
 - Fixed a potential SNMP OID value overflow issue (Issue #431)
 - Fixed an OpenSSL certificate loading issue (Issue #465)
 - Fixed Brazilian Portuguese translations (Issue #288)
+- Fixed `cupsd` default keychain location when building with OpenSSL
+  (Issue #529)
+- Fixed default color settings for CMYK printers as well (Issue #500)
 - Fixed duplicate PPD2IPP media-type names (Issue #688)
 - Fixed InputSlot heuristic for photo sizes smaller than 5x7" if there is no
   media-source in the request (Issue #569)
@@ -24,9 +27,7 @@ Changes in CUPS v2.4.3 (TBA)
 - Fixed memory leaks in `create_local_bg_thread()` (Issue #466)
 - Fixed media size tolerance in `ippeveprinter` (Issue #487)
 - Fixed passing command name without path into `ippeveprinter` (Issue #629)
-- Fixed `cupsd` default keychain location when building with OpenSSL
-  (Issue #529)
-- Fixed default color settings for CMYK printers as well (Issue #500)
+- Fixed saving strings file path in `printers.conf` (Issue #710)
 - Fixed TLS certificate generation bugs (Issue #652)
 - `ippDeleteValues` would not delete the last value (Issue #556)
 - Ignore some of IPP defaults if the application sends its PPD alternative

scheduler/printers.c

@@ -3942,6 +3942,16 @@ load_ppd(cupsd_printer_t *p)		/* I - Printer */
       * Loaded successfully!
       */
 
+     /*
+      * Set `strings` (source for printer-strings-uri IPP attribute)
+      * if printer's .strings file with localization exists.
+      */
+
+      if (!access(strings_name, R_OK))
+	cupsdSetString(&p->strings, strings_name);
+      else
+	cupsdClearString(&p->strings);
+
       return;
     }
   }