Update tests to avoid using trigraphs in C23 mode.

In C23 mode, C2.1.0.4.CC now tests that the former trigraph sequences are treated as regular characters (not trigraphs) in strings.

Tests/Conformance/C2.1.0.2.CC

@@ -4,6 +4,8 @@
 
 int printf(const char *, ...);
 
+#if __STDC_VERSION__ < 202311L
+
 ??=define ten 10                       /* ??= is '#' */
 
 int main (void)
@@ -43,3 +45,12 @@ int main (void)
 Fail:
    printf ("Failed Conformance Test 2.1.0.2\n");
   ??>                                  /* ??> is '}' */
+
+#else
+
+int main (void)
+  {
+  printf ("Passed Conformance Test 2.1.0.2\n");
+  }
+
+#endif

Tests/Conformance/C2.1.0.3.CC

@@ -7,6 +7,7 @@ int main (void)
   {
    char a;
 
+#if __STDC_VERSION__ < 202311L
    a = '??=';                          /* ??= is '#' */
    if (a != '#')
        goto Fail;
@@ -42,6 +43,7 @@ int main (void)
    a = '??>';                          /* ??> is '}' */
    if (a != '}')
        goto Fail;
+#endif
 
    printf ("Passed Conformance Test 2.1.0.3\n");
    return 0;

Tests/Conformance/C2.1.0.4.CC

@@ -9,8 +9,13 @@ int main (void)
   {
    char a [] = "??=??/boh??'??!??-??(??<??)??>boy";
 
+#if __STDC_VERSION__ < 202311L
    if ((strcmp (a, "#\boh^|~[{]}boy")) != 0)
        goto Fail;
+#else
+   if ((strcmp (a, "?" "?=?" "?/boh?" "?'?" "?!?" "?-?" "?(?" "?<?" "?)?" "?>boy")) != 0)
+       goto Fail;
+#endif
 
    printf ("Passed Conformance Test 2.1.0.4\n");
    return 0;