meson: drop libsystemd_network from several binaries

This reduces the size of udevadm:

Before:
```
$ ll udevadm
-rwxrwxr-x 1 watanabe watanabe 1203800 Oct 29 01:36 udevadm
```

After:
```
$ ll udevadm
-rwxrwxr-x 1 watanabe watanabe 1094384 Oct 29 01:38 udevadm
```

meson.build

@@ -3188,7 +3188,6 @@ public_programs += executable(
         c_args : '-DLOG_REALM=LOG_REALM_UDEV',
         include_directories : includes,
         link_with : [libudev_core,
-                     libsystemd_network,
                      libudev_static],
         dependencies : [versiondep,
                         threads,

src/fuzz/meson.build

@@ -108,7 +108,6 @@ fuzzers += [
         [['src/fuzz/fuzz-udev-rules.c'],
          [libudev_core,
           libudev_static,
-          libsystemd_network,
           libshared],
          [threads,
           libacl]],

src/libsystemd-network/meson.build

@@ -17,6 +17,7 @@ sources = files('''
         arp-util.h
         arp-util.c
         network-internal.c
+        network-internal.h
         sd-ndisc.c
         ndisc-internal.h
         ndisc-router.h
@@ -42,10 +43,7 @@ sources = files('''
         sd-lldp.c
 '''.split())
 
-network_internal_h = files('network-internal.h')
-
 libsystemd_network = static_library(
         'systemd-network',
         sources,
-        network_internal_h,
         include_directories : includes)

src/network/meson.build

@@ -171,7 +171,7 @@ systemd_networkd_wait_online_sources = files('''
         wait-online/manager.c
         wait-online/manager.h
         wait-online/wait-online.c
-'''.split()) + network_internal_h
+'''.split())
 
 networkctl_sources = files('networkctl.c')
 
@@ -214,7 +214,6 @@ if conf.get('ENABLE_NETWORKD') == 1
         libnetworkd_core = static_library(
                 'networkd-core',
                 sources,
-                network_internal_h,
                 networkd_gperf_c,
                 networkd_network_gperf_c,
                 netdev_gperf_c,

src/test/meson.build

@@ -126,8 +126,7 @@ tests += [
 
         [['src/test/test-dns-domain.c'],
          [libcore,
-          libshared,
+          libshared],
-          libsystemd_network],
          []],
 
         [['src/test/test-boot-timestamps.c'],
@@ -529,7 +528,6 @@ tests += [
           libjournal_core,
           libudev_core,
           libudev_static,
-          libsystemd_network,
           libshared],
          [threads,
           libseccomp,
@@ -765,7 +763,6 @@ tests += [
         [['src/test/test-udev.c'],
          [libudev_core,
           libudev_static,
-          libsystemd_network,
           libshared],
          [threads,
           librt,

src/udev/meson.build

@@ -202,7 +202,6 @@ fuzzers += [
           'src/fuzz/fuzz.h'],
          [libudev_core,
           libudev_static,
-          libsystemd_network,
           libshared],
          [threads,
           libacl]],