[gnome-system-monitor] Fix desktop files generation by adding rules to merge translations

[Robert Roth <robertroth src gnome org>]

commit 9b16f47c7b91b60be380994b4d9a02297d87d8f1
Author: Ting-Wei Lan <lantw src gnome org>
Date:   Sun Jan 21 00:12:52 2018 +0800

    Fix desktop files generation by adding rules to merge translations
    
    https://bugzilla.gnome.org/show_bug.cgi?id=790570

 Makefile.am |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 993943d..16c0460 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -36,6 +36,8 @@ $(polkit_policy_DATA): %.policy: %.policy.in
 Applicationsdir = $(datadir)/applications
 Applications_in_files = gnome-system-monitor.desktop.in gnome-system-monitor-kde.desktop.in
 Applications_DATA = $(Applications_in_files:.desktop.in=.desktop)
+$(Applications_DATA): %.desktop: %.desktop.in
+       $(AM_V_GEN)$(MSGFMT) --desktop --template $< -d $(top_srcdir)/po -o $@
 
 appdatadir = $(datadir)/metainfo
 appdata_DATA = $(appdata_in_files:.xml.in=.xml)