build: fix -Dagent=true -Dlibsysprof=false

The agent is statically linked so that it doesn't require using a properly
working libsysprof to be installed. This ensures that it continues to build
properly in that case so it can be used from org.gnome.Sdk.

meson.build

@@ -28,7 +28,7 @@ polkit_req_version = '>= 0.105'
 
 cc = meson.get_compiler('c')
 
-if get_option('libsysprof')
+if get_option('libsysprof') or get_option('agent')
   add_languages('cpp', native: false)
   cxx = meson.get_compiler('cpp')
 endif
@@ -197,6 +197,14 @@ int main(void) {
   config_h.set10('HAVE_STDATOMIC_H', true)
 endif
 
+if get_option('libsysprof') or get_option('agent')
+  needs_service_access = true
+endif
+
+if needs_service_access or get_option('sysprofd') == 'bundled'
+  install_service_files = true
+endif
+
 subdir('src')
 subdir('data')
 subdir('po')