os: fix link failure on Illumos

On SunOS, the BSD socket API as well as hostname lookups isn't
implemented in libc, but separate libraries. We need to link them
explicitly.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>

os/meson.build

@@ -65,6 +65,8 @@ if host_machine.system() == 'sunos'
     os_c_args += '-D_XOPEN_SOURCE=1'
     os_c_args += '-D_XOPEN_SOURCE_EXTENDED=1'
     os_c_args += '-D__EXTENSIONS__'
+    os_dep += cc.find_library('socket')
+    os_dep += cc.find_library('nsl')
 endif
 
 if get_option('xres')