patch 8.2.1548: cannot move position of "%%" in message translations

Problem:    Cannot move position of "%%" in message translations. (Emir Sarı)
Solution:   Improve the check script.
diff --git a/src/po/check.vim b/src/po/check.vim
index 454a053..f94070f 100644
--- a/src/po/check.vim
+++ b/src/po/check.vim
@@ -22,6 +22,7 @@
 
   " remove '%', not used for formatting.
   let idline = substitute(idline, "'%'", '', 'g')
+  let idline = substitute(idline, "%%", '', 'g')
 
   " remove '%' used for plural forms.
   let idline = substitute(idline, '\\nPlural-Forms: .\+;\\n', '', '')
diff --git a/src/version.c b/src/version.c
index b071bf5..83bb9dc 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1548,
+/**/
     1547,
 /**/
     1546,