Adding dpkg-mergechangelogs merge driver for debian/changelog files.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

debian/git.install

@@ -4,3 +4,4 @@ contrib/completion/git-prompt.sh => usr/lib/git-core/git-sh-prompt
 debian/git-prompt.completion => etc/bash_completion.d/git-prompt
 contrib/hooks usr/share/git-core/contrib
 debian/local/gitconfig => /etc/gitconfig
+debian/local/gitattributes => /etc/gitattributes

debian/local/gitattributes

@@ -0,0 +1,3 @@
+# /etc/gitattributes
+
+debian/changelog merge=dpkg-mergechangelogs

debian/local/gitconfig

@@ -19,3 +19,8 @@
 
 [log]
 	follow = true
+
+[merge "dpkg-mergechangelogs"]
+	# depends: dpkg-dev
+	name = debian/changelog merge driver
+	driver = dpkg-mergechangelogs -m %O %A %B %A