[shotwell] Enable SQL debugging through environment variable

[Jens Georg <jensgeorg src gnome org>]

commit ece15b26e968e76a9165ba4fdacfcde5a425fc38
Author: Jens Georg <mail jensge org>
Date:   Sun Oct 16 22:20:14 2016 +0200

    Enable SQL debugging through environment variable
    
    Signed-off-by: Jens Georg <mail jensge org>

 src/db/DatabaseTable.vala |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)
---
diff --git a/src/db/DatabaseTable.vala b/src/db/DatabaseTable.vala
index 09c026f..5ec5be1 100644
--- a/src/db/DatabaseTable.vala
+++ b/src/db/DatabaseTable.vala
@@ -49,9 +49,13 @@ public abstract class DatabaseTable {
                     e.message));
             }
         }
-#if SQLITE_DEBUG
-        db.trace (on_trace);
-#endif
+
+        unowned string? sql_debug = Environment.get_variable
+                                                         ("SHOTWELL_SQL_DEBUG");
+
+        if (sql_debug != null && sql_debug != "") {
+            db.trace (on_trace);
+        }
     }
 
     public static void on_trace (string message) {