Introduce next Japanese gengou era 'Reiwa'

starting from 2019-05-01, which has been announced officially.

This fills the provisional slot acknowledged at
cacbb0fa.

Change-Id: Ifb12e6afaad4c66d455f664b46ec946e80324e87
Reviewed-on: https://gerrit.libreoffice.org/70028
Tested-by: Jenkins
Reviewed-by: Eike Rathke <erack@redhat.com>

i18npool/source/calendar/calendar_gregorian.cxx

@@ -209,7 +209,7 @@ static const Era gengou_eraArray[] = {
     {1912,  7, 30, 0},  // Taisho
     {1926, 12, 25, 0},  // Showa
     {1989,  1,  8, 0},  // Heisei
-    {2019,  5,  1, 0},  //(Naruhito) (TODO: real era name not known yet (2018-07-26))
+    {2019,  5,  1, 0},  // Reiwa
     {0, 0, 0, 0}
 };
 Calendar_gengou::Calendar_gengou() : Calendar_gregorian(gengou_eraArray)

i18npool/source/localedata/data/ja_JP.xml

@@ -481,11 +481,9 @@
           <DefaultFullName>平成</DefaultFullName>
         </Era>
         <Era>
-          <!-- TODO: Naruhito is only the emperor's name, the era name and
-               abbreviation and full name are not known yet (2018-07-26) -->
-          <EraID>Naruhito</EraID>
-          <DefaultAbbrvName>Na</DefaultAbbrvName>
-          <DefaultFullName>Naruhito</DefaultFullName>
+          <EraID>Reiwa</EraID>
+          <DefaultAbbrvName>令</DefaultAbbrvName>
+          <DefaultFullName>令和</DefaultFullName>
         </Era>
       </Eras>
       <StartDayOfWeek>

svl/source/numbers/zformat.cxx

@@ -3476,7 +3476,7 @@ void SvNumberformat::ImpAppendEraG( OUStringBuffer& OutString,
             cEra = 'H';
             break;
         case 5:
-            cEra = 'N';     /* TODO: the real one letter era name is not known yet (2018-07-26) */
+            cEra = 'R';
             break;
         default:
             cEra = '?';