[gnome-builder] diagnostics: specify ref_count as volatile

[Christian Hergert <chergert src gnome org>]

commit 3384f5f8060184667c1295a0dd3086331e9f6cb2
Author: Christian Hergert <chergert redhat com>
Date:   Wed Jan 3 01:11:33 2018 -0800

    diagnostics: specify ref_count as volatile

 src/libide/diagnostics/ide-diagnostics-manager.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/libide/diagnostics/ide-diagnostics-manager.c 
b/src/libide/diagnostics/ide-diagnostics-manager.c
index bb916b1..32fe1a9 100644
--- a/src/libide/diagnostics/ide-diagnostics-manager.c
+++ b/src/libide/diagnostics/ide-diagnostics-manager.c
@@ -41,7 +41,7 @@ typedef struct
    * only. This is used so that providers can have access to the group even
    * after the group has been removed from the IdeDiagnosticsManager.
    */
-  gint ref_count;
+  volatile gint ref_count;
 
   /*
    * This is our identifier for the diagnostics. We use this as the key in