Bump Cockpit pkg/lib to 249

Cockpit 247 changed cockpit-po-plugin.js to always expect a line number
in msgid references [1]. Also sync manifest2po from Cockpit 249 to
generate that reference for manifests, so that they keep getting
included into the translation js.

[1] 0ecc3a705d

Makefile

@@ -154,7 +154,7 @@ test/common:
 # checkout Cockpit's PF/React/build library; again this has no API stability guarantee, so check out a stable tag
 $(LIB_TEST):
 	flock Makefile sh -ec '\
-	    git fetch --depth=1 https://github.com/cockpit-project/cockpit.git 242; \
+	    git fetch --depth=1 https://github.com/cockpit-project/cockpit.git 249; \
 	    git checkout --force FETCH_HEAD -- pkg/lib; \
 	    git reset -- pkg/lib'
 	mv pkg/lib src/ && rmdir -p pkg

po/de.po

@@ -22,7 +22,7 @@ msgstr "Cockpit Bausatz"
 msgid "Running on $0"
 msgstr "Läuft auf $0"
 
-#: src/manifest.json
+#: src/manifest.json:0
 msgid "Starter Kit"
 msgstr "Bausatz"
 

po/manifest2po

@@ -100,7 +100,7 @@ function process_keywords(keywords) {
         v.matches.forEach(keyword =>
             push({
                 msgid: keyword,
-                locations: [ filename ]
+                locations: [ filename + ":0" ]
             })
         );
     });
@@ -110,7 +110,7 @@ function process_docs(docs) {
     docs.forEach(doc => {
         push({
             msgid: doc.label,
-            locations: [ filename ]
+            locations: [ filename + ":0" ]
         })
     });
 }
@@ -120,7 +120,7 @@ function process_menu(menu) {
         if (menu[m].label) {
             push({
                 msgid: menu[m].label,
-                locations: [ filename ]
+                locations: [ filename + ":0" ]
             });
         }
         if (menu[m].keywords)