syntax-check: Add the rule to forbid whitespace before ";"

syntax-check: Add the rule to forbid whitespace before ";"

Only a few cases are allowed:

1) The expression is empty for "for" loop, E.g.

  for (i = 0; ; i++)

2) An empty statement

  while (write(statuswrite, &status, 1) == -1 &&
         errno == EINTR)
      ; /* empty */

3) ";" is inside double-quote, I.e, as part of const string. E.g.

  vshPrint(ctl, "a ; b ; cd;\n");

The "for" loop in src/rpc/virnettlscontext.c is the special case,
1) applies for it, so change it together in this patch.