yyinput() returns int

Change-Id: I2e1958bff9778bab65b5c972bc9e0721a86546f5
Reviewed-on: https://gerrit.libreoffice.org/68630
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

l10ntools/source/xrmlex.l

@@ -134,7 +134,7 @@ static int bText=0;
 
 
 "<!--"  {
-    char c1 = 0, c2 = 0;
+    int c1 = 0, c2 = 0;
     int c3 = yyinput();
     char pChar[2];
     pChar[1] = 0x00;