libnetfilter-queue: Add missing libmnl to DEPENDS

otherwise Errors are seen with sstate

| configure:11780: error: Package requirements (libmnl >= 1.0.3) were
not met:
|
| No package 'libmnl' found
|
| Consider adjusting the PKG_CONFIG_PATH environment variable if you
| installed software in a non-standard prefix.

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Joe MacDonald <joe.macdonald@windriver.com>