qemu: add PACKAGECONFIG for vnc, libcurl, nss, uuid, curses, gtk+, libcap-ng

Use PACKAGECONFIG to explicitly address vnc, libcurl, nss, uuid, curses, gtk+,
libcap-ng dependencies rather than tested by configure.

It avoided potential errors while multiple builds shared a common state_cache.

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>