build: drop legacy v2 service and simplify build system

This removes -Dagent and just uses -Dtools as it only affects sysprof-cli
and sysprof-agent. We still need to patch sysprof-cli for recent changes
as we did for sysprof-agent though.

Additionally, we haven't used the v2 service in forever, so drop that as
I can't imagine anyone has been using it.

src/meson.build

@@ -15,18 +15,11 @@ if install_service_files
       'org.gnome.Sysprof2.xml',
       'org.gnome.Sysprof3.Profiler.xml',
       'org.gnome.Sysprof3.Service.xml',
-      'org.gnome.Sysprof.Agent.xml'
     ],
     install_dir: join_paths(datadir, 'dbus-1/interfaces'),
   )
 endif
 
-ipc_include_dirs = include_directories('.')
-
-stackstash_sources = files('stackstash.c')
-
-helpers_sources = files('helpers.c')
-
 if need_libsysprof_capture
   subdir('libsysprof-capture')
 endif
@@ -43,9 +36,12 @@ endif
 if get_option('sysprofd') == 'bundled'
   subdir('sysprofd')
 endif
+
 if get_option('gtk')
   subdir('sysprof')
 endif
-if get_option('agent')
+
+if get_option('tools')
   subdir('sysprof-agent')
+  subdir('sysprof-cli')
 endif