main/lxc: add init.lxc.static

this is needed for lxc-execute to work
add libcap-static to makedepends
fixes #10821
5 jobs for !128 with lxc-3.2.1-r1 in 8 minutes and 57 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Lint
passed lint #1119
docker-alpine x86_64

00:00:20

 
  Build
passed build-ppc64le #1123
docker-alpine ci-build ppc64le

00:01:14

passed build-s390x #1122
docker-alpine ci-build s390x

00:08:36

passed build-x86 #1121
docker-alpine ci-build x86

00:01:46

passed build-x86_64 #1120
docker-alpine ci-build x86_64

00:01:38