[tests] Update a test to trigger a warning in doInit

tests/syntax/initializer.i

@@ -31,6 +31,6 @@ struct signal tsig [3] = { 0.1, INVALID, 3, VALID };
 
 void main() {
   static unsigned char STR [] = { "123456" };
-
+  char ch[3] = "hello"; // Emit a warning
   int i = STR[2];
 }

tests/syntax/oracle/initializer.res.oracle

@@ -2,6 +2,7 @@
 [kernel:parser:decimal-float] initializer.i:29: Warning: 
   Floating-point constant 0.1 is not represented exactly. Will use 0x1.999999999999ap-4.
   (warn-once: no further messages from category 'parser:decimal-float' will be emitted)
+[kernel] initializer.i:34: Warning: Too many initializers for character array ch
 /* Generated by Frama-C */
 enum bool {
     INVALID = 0,
@@ -57,6 +58,7 @@ static unsigned char main_STR[7] =
    (unsigned char)'\000'};
 void main(void)
 {
+  char ch[3] = {(char)'h', (char)'e', (char)'l'};
   int i = (int)main_STR[2];
   return;
 }