[geary] Fix meson build when libmessaging-menu is available.

[Michael Gratton <mjog src gnome org>]

commit afb236517f954d8f02779dd76b58ca26cf4692ca
Author: Michael James Gratton <mike vee net>
Date:   Tue Dec 12 14:35:16 2017 +1100

    Fix meson build when libmessaging-menu is available.
    
    Since libmessaging-menu has a either a broken pkg_config file or a dumb
    VAPI name, we need to detect the library and the VAPI in two steps, then
    add them both as dependencies.

 meson.build            |    2 +-
 src/client/meson.build |    6 ++++++
 2 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/meson.build b/meson.build
index 8dcda82..2b1d7f1 100644
--- a/meson.build
+++ b/meson.build
@@ -71,7 +71,7 @@ libunwind = declare_dependency(
 )
 
 libunity = dependency('unity', version: '>= 5.12.0', required: false)
-libmessagingmenu = dependency('messaging-menu', version: '>= 12.10.2', required: false)
+libmessagingmenu = meson.get_compiler('c').find_library('libmessaging-menu', required: false)
 sqlite = dependency('sqlite3')
 if sqlite.version().version_compare('>= 3.12')
   if not cc.has_header_symbol('sqlite3.h', 'SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER')
diff --git a/src/client/meson.build b/src/client/meson.build
index 03af603..33851bf 100644
--- a/src/client/meson.build
+++ b/src/client/meson.build
@@ -122,7 +122,13 @@ geary_client_dependencies = [
 ]
 
 if libmessagingmenu.found()
+  messagingmenu_vapi = meson.get_compiler('vala').find_library(
+      'MessagingMenu-1.0',
+      dirs: '/usr/share/vala/vapi',
+      required: true
+  )
   geary_client_dependencies += libmessagingmenu
+  geary_client_dependencies += messagingmenu_vapi
 endif
 if libunity.found()
   geary_client_dependencies += libunity