checkpatch: add check for `while` and `for`

Adding check for `while` and `for` statements, which condition has more than
one line.

The former checkpatch.pl can check `if` statement, which condition has more
than one line, whether block misses brace round, like this:
'''
if (cond1 ||
    cond2)
    statement;
'''
But it doesn't do the same check for `for` and `while` statements.

Using `(?:...)` instead of `(...)` in regex pattern catch.
Because `(?:...)` is faster and avoids unwanted side-effect.

Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
Suggested-by: Eric Blake <eblake@redhat.com>
Suggested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Su Hang <suhang16@mails.ucas.ac.cn>
Message-Id: <1520319890-19761-1-git-send-email-suhang16@mails.ucas.ac.cn>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>