insane.bbclass:buildpaths: ignore ipkg/dpkg's CONTROL dir

insane.bbclass:buildpaths: ignore ipkg/dpkg's CONTROL dir

Fixed race issue when:
WARN_QA_append = " buildpaths"
PACKAGE_CLASSES = "package_ipk"
$ bitbake e2fsprogs

[snip]
 *** 0595:    with open(path) as f:
     0596:        file_content = f.read()
     0597:        if tmpdir in file_content:
     0598:            messages["buildpaths"] = "File %s in package contained reference to tmpdir" % package_qa_clean_path(path,d)
     0599:
Exception: IOError: [Errno 2] No such file or directory: '/path/to/tmp/work/core2-64-poky-linux/e2fsprogs/1.42.9-r0/packages-split/e2fsprogs-ptest/CONTROL/control'

The similar to package_deb.

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>