[shotwell] Fix typo in _GIT_VERSION predefine

[Jens Georg <jensgeorg src gnome org>]

commit b8f1486834e24d0cba79d809d96093fd05f0e9d5
Author: Joerg C. Frings-Fuerst <bug-reports-extern jff-webhosting net>
Date:   Tue May 1 15:54:00 2018 +0000

    Fix typo in _GIT_VERSION predefine
    
    https://bugzilla.gnome.org/show_bug.cgi?id=795719

 src/Resources.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/Resources.vala b/src/Resources.vala
index 2aa32c7..70c4a7b 100644
--- a/src/Resources.vala
+++ b/src/Resources.vala
@@ -18,7 +18,7 @@ namespace Resources {
     public const string APP_DIRECT_ROLE = _("Photo Viewer");
     public const string APP_VERSION = _VERSION;
 
-#if _GITVERSION
+#if _GIT_VERSION
     public const string? GIT_VERSION = _GIT_VERSION;
 #else
     public const string? GIT_VERSION = null;