Unix: Change debugging options

The old behavior was that enabling debugging did many nontrivial changes
in BIRD behavior. The patch changes it that these changes are generally
independent. Compiling with --enable-debug now just enables compile-time
debug macros, but do not automatically activate debug mode (-d) nor local
mode (-l). Debug mode with output to file (-D) do not force foreground
mode (-f), therefore there is no need for backgroud option (-b), which is
removed. Also fixes a bug when the default log target in -D mode was
stderr instead of given debug file.
32 jobs for int-new in 7 minutes and 21 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Image
passed #201608
dind allowed to fail
docker_centos-6-amd64

00:00:26

passed #201609
dind allowed to fail
docker_centos-7-amd64

00:00:26

passed #201598
dind allowed to fail
docker_debian-7-amd64

00:00:24

passed #201602
dind allowed to fail
docker_debian-7-i386

00:00:27

passed #201599
dind allowed to fail
docker_debian-8-amd64

00:00:25

passed #201603
dind allowed to fail
docker_debian-8-i386

00:00:24

passed #201600
dind allowed to fail
docker_debian-9-amd64

00:00:25

passed #201604
dind allowed to fail
docker_debian-9-i386

00:00:24

passed #201601
dind allowed to fail
docker_debian-testing-amd64

00:00:25

passed #201605
dind allowed to fail
docker_debian-testing-i386

00:00:24

passed #201606
dind allowed to fail
docker_fedora-25-amd64

00:00:25

passed #201607
dind allowed to fail
docker_fedora-26-amd64

00:00:25

passed #201610
dind allowed to fail
docker_opensuse-42_3-amd64

00:00:27

passed #201611
dind allowed to fail
docker_ubuntu-14_04-amd64

00:00:27

passed #201612
dind allowed to fail
docker_ubuntu-16_04-amd64

00:00:28

 
  Build
passed #201619
amd64 linux docker
build-centos-6-amd64

00:00:58

passed #201620
amd64 linux docker
build-centos-7-amd64

00:00:59

passed #201613
amd64 linux docker
build-debian-7-amd64

00:00:59

passed #201624
amd64 linux docker
build-debian-7-i386

00:00:47

passed #201614
amd64 linux docker
build-debian-8-amd64

00:01:01

passed #201625
amd64 linux docker
build-debian-8-i386

00:00:50

passed #201615
amd64 linux docker
build-debian-9-amd64

00:01:02

passed #201626
amd64 linux docker
build-debian-9-i386

00:00:52

passed #201616
amd64 linux docker
build-debian-testing-amd64

00:01:03

passed #201627
amd64 linux docker
build-debian-testing-i386

00:00:55

passed #201617
amd64 linux docker
build-fedora-25-amd64

00:01:02

passed #201618
amd64 linux docker
build-fedora-26-amd64

00:01:01

passed #201628
amd64 freebsd
build-freebsd-11-amd64

00:05:58

passed #201629
i386 freebsd
build-freebsd-11-i386

00:05:06

passed #201621
amd64 linux docker
build-opensuse-42_3-amd64

00:00:58

passed #201622
amd64 linux docker
build-ubuntu-14_04-amd64

00:01:01

passed #201623
amd64 linux docker
build-ubuntu-16_04-amd64

00:00:43