patch 8.1.0306: plural messages are not translated properly

Problem:    Plural messages are not translated properly.
Solution:   Add more usage of NGETTEXT(). (Sergey Alyoshin)
diff --git a/src/fileio.c b/src/fileio.c
index 7bceb75..d00dc5e 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -5349,16 +5349,11 @@
 		"%ldL, %lldC", lnum, (long long)nchars);
     else
     {
-	if (lnum == 1)
-	    STRCPY(p, _("1 line, "));
-	else
-	    sprintf((char *)p, _("%ld lines, "), lnum);
+	sprintf((char *)p, NGETTEXT("%ld line, ", "%ld lines, ", lnum), lnum);
 	p += STRLEN(p);
-	if (nchars == 1)
-	    STRCPY(p, _("1 character"));
-	else
-	    vim_snprintf((char *)p, IOSIZE - (p - IObuff),
-		    _("%lld characters"), (long long)nchars);
+	vim_snprintf((char *)p, IOSIZE - (p - IObuff),
+		NGETTEXT("%lld character", "%lld characters", nchars),
+		(long long)nchars);
     }
 }