qt: Add missing header redirection

* lang/qt/src/keyformailboxjob.h,
lang/qt/src/qgpgmekeyformailboxjob.h: Fix includes.

--
This ensures that when building qgpgme you do not need an installed
gpgme++.

lang/qt/src/keyformailboxjob.h

@@ -36,7 +36,12 @@
 
 #include "job.h"
 
+#ifdef BUILDING_QGPGME
+# include "key.h"
+#else
 # include <gpgme++/key.h>
+#endif
+
 namespace GpgME
 {
 class Error;

lang/qt/src/qgpgmekeyformailboxjob.h

@@ -38,8 +38,13 @@
 
 #include "threadedjobmixin.h"
 
+#ifdef BUILDING_QGPGME
+# include "keylistresult.h"
+# include "key.h"
+#else
 # include <gpgme++/keylistresult.h>
 # include <gpgme++/key.h>
+#endif
 
 namespace QGpgME
 {