[planner] Libplannerapp does mathematics.

[Alexandre Franke <afranke src gnome org>]

commit b5db0f39763ce7a2b95b5029e28da0d6dac10b27
Author: Ahmed <ahmed baizid org>
Date:   Sat Jan 17 17:22:53 2015 +0100

    Libplannerapp does mathematics.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=697712

 src/Makefile.am |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/Makefile.am b/src/Makefile.am
index 7191da2..538583b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -125,6 +125,8 @@ libplannerapp_la_SOURCES =                  \
        $(resource_source)              \
        $(usage_source)
 
+libplannerapp_la_LIBADD = -lm
+
 gantt_task_source =                    \
        planner-gantt-background.c      \
        planner-gantt-background.h      \