[folks] build: Fix tracker backend typelib generation

[Niels De Graef <nielsdg src gnome org>]

commit 8db8fd598b30f7268b4bd37cb5659dd3b31d792e
Author: Iñigo Martínez <inigomartinez gmail com>
Date:   Wed Apr 17 13:01:11 2019 +0200

    build: Fix tracker backend typelib generation
    
    The generation of the tracker backend typelib,
    `FolksTracker-0.6.typelib` fails because `Folks-0.6.gir` cannot be
    found.
    
    This has been fixed by including `folks` build directory so the
    `Folks-0.6.gir` file can be found.

 backends/tracker/lib/meson.build | 1 +
 folks/meson.build                | 2 ++
 2 files changed, 3 insertions(+)
---
diff --git a/backends/tracker/lib/meson.build b/backends/tracker/lib/meson.build
index ffdb2f64..4fa35de8 100644
--- a/backends/tracker/lib/meson.build
+++ b/backends/tracker/lib/meson.build
@@ -51,6 +51,7 @@ tracker_backendlib = shared_library('folks-@0@'.format(tracker_backend_name),
 custom_target(tracker_backendlib_gir_name + ' typelib',
   command: [ g_ir_compiler,
     '--output', '@OUTPUT@',
+    '--includedir', folks_build_dir,
     meson.current_build_dir() / (tracker_backendlib_gir_name + '.gir')
   ],
   output: tracker_backendlib_gir_name + '.typelib',
diff --git a/folks/meson.build b/folks/meson.build
index 490262c6..d40a7ddc 100644
--- a/folks/meson.build
+++ b/folks/meson.build
@@ -1,3 +1,5 @@
+folks_build_dir = meson.current_build_dir()
+
 # Internal library
 libfolks_internal_sources = [
   'internal.vala',