[gtk: 1/2] gdkglcontext: Fix build with MSVC

[Xavier Claessens <xclaesse src gnome org>]

commit be8246a6cb0ebb82ed6498142d3388747d272f86
Author: Xavier Claessens <xavier claessens collabora com>
Date:   Sun Oct 18 17:14:22 2020 -0400

    gdkglcontext: Fix build with MSVC
    
    GLDEBUGPROC callback is defined with APIENTRY which is a windows
    specific calling convention. That macro expands to nothing when building
    on other platforms.
    
    Fixes: #3268.

 gdk/gdkglcontext.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gdk/gdkglcontext.c b/gdk/gdkglcontext.c
index 135db30140..5d73080b9b 100644
--- a/gdk/gdkglcontext.c
+++ b/gdk/gdkglcontext.c
@@ -864,7 +864,7 @@ gdk_gl_context_get_use_es (GdkGLContext *context)
   return priv->use_es > 0;
 }
 
-static void
+static void APIENTRY
 gl_debug_message_callback (GLenum        source,
                            GLenum        type,
                            GLuint        id,