Populate missing GDateTime format strings

Use the glibc locale database to add GDateTime strings only for those locales
that had not specifically added them for themselves.

Some locales have different translations from what is in the C library and we
leave those alone with this commit.

po/fa.po

@@ -173,19 +173,19 @@ msgstr ""
 #: ../glib/gdatetime.c:207
 msgctxt "GDateTime"
 msgid "%a %b %e %H:%M:%S %Y"
-msgstr ""
+msgstr "‫%A %Oe %B %Oy، %OH:%OM:%OS‬"
 
 #. Translators: this is the preferred format for expressing the date
 #: ../glib/gdatetime.c:210
 msgctxt "GDateTime"
 msgid "%m/%d/%y"
-msgstr ""
+msgstr "%Oy/%Om/%Od"
 
 #. Translators: this is the preferred format for expressing the time
 #: ../glib/gdatetime.c:213
 msgctxt "GDateTime"
 msgid "%H:%M:%S"
-msgstr ""
+msgstr "%OH:%OM:%OS"
 
 #. Translators: this is the preferred format for expressing 12 hour time
 #: ../glib/gdatetime.c:216
@@ -196,37 +196,37 @@ msgstr ""
 #: ../glib/gdatetime.c:229
 msgctxt "full month name"
 msgid "January"
-msgstr ""
+msgstr "ژانویه"
 
 #: ../glib/gdatetime.c:231
 msgctxt "full month name"
 msgid "February"
-msgstr ""
+msgstr "فوریه"
 
 #: ../glib/gdatetime.c:233
 msgctxt "full month name"
 msgid "March"
-msgstr ""
+msgstr "مارس"
 
 #: ../glib/gdatetime.c:235
 msgctxt "full month name"
 msgid "April"
-msgstr ""
+msgstr "آوریل"
 
 #: ../glib/gdatetime.c:237
 msgctxt "full month name"
 msgid "May"
-msgstr ""
+msgstr "مه"
 
 #: ../glib/gdatetime.c:239
 msgctxt "full month name"
 msgid "June"
-msgstr ""
+msgstr "ژوئن"
 
 #: ../glib/gdatetime.c:241
 msgctxt "full month name"
 msgid "July"
-msgstr ""
+msgstr "ژوئیه"
 
 #: ../glib/gdatetime.c:243
 msgctxt "full month name"
@@ -256,37 +256,37 @@ msgstr ""
 #: ../glib/gdatetime.c:266
 msgctxt "abbreviated month name"
 msgid "Jan"
-msgstr ""
+msgstr "ژانویه"
 
 #: ../glib/gdatetime.c:268
 msgctxt "abbreviated month name"
 msgid "Feb"
-msgstr ""
+msgstr "فوریه"
 
 #: ../glib/gdatetime.c:270
 msgctxt "abbreviated month name"
 msgid "Mar"
-msgstr ""
+msgstr "مارس"
 
 #: ../glib/gdatetime.c:272
 msgctxt "abbreviated month name"
 msgid "Apr"
-msgstr ""
+msgstr "آوریل"
 
 #: ../glib/gdatetime.c:274
 msgctxt "abbreviated month name"
 msgid "May"
-msgstr ""
+msgstr "مه"
 
 #: ../glib/gdatetime.c:276
 msgctxt "abbreviated month name"
 msgid "Jun"
-msgstr ""
+msgstr "ژوئن"
 
 #: ../glib/gdatetime.c:278
 msgctxt "abbreviated month name"
 msgid "Jul"
-msgstr ""
+msgstr "ژوئیه"
 
 #: ../glib/gdatetime.c:280
 msgctxt "abbreviated month name"
@@ -316,72 +316,72 @@ msgstr ""
 #: ../glib/gdatetime.c:303
 msgctxt "full weekday name"
 msgid "Monday"
-msgstr ""
+msgstr "دوشنبه"
 
 #: ../glib/gdatetime.c:305
 msgctxt "full weekday name"
 msgid "Tuesday"
-msgstr ""
+msgstr "سه‌شنبه"
 
 #: ../glib/gdatetime.c:307
 msgctxt "full weekday name"
 msgid "Wednesday"
-msgstr ""
+msgstr "چهارشنبه"
 
 #: ../glib/gdatetime.c:309
 msgctxt "full weekday name"
 msgid "Thursday"
-msgstr ""
+msgstr "پنجشنبه"
 
 #: ../glib/gdatetime.c:311
 msgctxt "full weekday name"
 msgid "Friday"
-msgstr ""
+msgstr "جمعه"
 
 #: ../glib/gdatetime.c:313
 msgctxt "full weekday name"
 msgid "Saturday"
-msgstr ""
+msgstr "شنبه"
 
 #: ../glib/gdatetime.c:315
 msgctxt "full weekday name"
 msgid "Sunday"
-msgstr ""
+msgstr "یکشنبه"
 
 #: ../glib/gdatetime.c:330
 msgctxt "abbreviated weekday name"
 msgid "Mon"
-msgstr ""
+msgstr "دوشنبه"
 
 #: ../glib/gdatetime.c:332
 msgctxt "abbreviated weekday name"
 msgid "Tue"
-msgstr ""
+msgstr "سه‌شنبه"
 
 #: ../glib/gdatetime.c:334
 msgctxt "abbreviated weekday name"
 msgid "Wed"
-msgstr ""
+msgstr "چهارشنبه"
 
 #: ../glib/gdatetime.c:336
 msgctxt "abbreviated weekday name"
 msgid "Thu"
-msgstr ""
+msgstr "پنجشنبه"
 
 #: ../glib/gdatetime.c:338
 msgctxt "abbreviated weekday name"
 msgid "Fri"
-msgstr ""
+msgstr "جمعه"
 
 #: ../glib/gdatetime.c:340
 msgctxt "abbreviated weekday name"
 msgid "Sat"
-msgstr ""
+msgstr "شنبه"
 
 #: ../glib/gdatetime.c:342
 msgctxt "abbreviated weekday name"
 msgid "Sun"
-msgstr ""
+msgstr "یکشنبه"
 
 #: ../glib/gdir.c:115 ../glib/gdir.c:138
 #, c-format