Add *.host.mk to .gitignore.

TBR=kjellander@webrtc.org
BUG=none

Review URL: https://webrtc-codereview.appspot.com/717012

git-svn-id: http://webrtc.googlecode.com/svn/trunk@2588 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/.gitignore b/.gitignore
index c27b166..29ef23e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+*.host.mk
 *.target.mk
 *.Makefile
 *.ncb