[gnome-photos/sam/tracker3: 26/28] Fix build failure due to undefined M_PI constant

[Sam Thursfield <sthursfield src gnome org>]

commit 7c98a884ba6a26795ea25a8780002ac101036887
Author: Sam Thursfield <sam afuera me uk>
Date:   Wed May 27 13:07:58 2020 +0200

    Fix build failure due to undefined M_PI constant
    
    The <math.h> header needs to be included.
    
    Previously I suppose libtracker-sparql.h pulled this in.

 src/photos-utils.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/photos-utils.c b/src/photos-utils.c
index 401f52ba..c638297b 100644
--- a/src/photos-utils.c
+++ b/src/photos-utils.c
@@ -30,6 +30,7 @@
 #include <glib.h>
 #include <tracker-sparql.h>
 #include <libgd/gd.h>
+#include <math.h>
 
 #include "photos-application.h"
 #include "photos-device-item.h"