Remove Git ignore exclusion of .sha1 files

This exclusion could cause invalid .sha1 files to be left
in resources on the trybots instead of being wiped.

BUG=4267
TBR=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/39929004

Cr-Commit-Position: refs/heads/master@{#8327}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8327 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/.gitignore b/.gitignore
index 7d7e70d..5dc7251 100644
--- a/.gitignore
+++ b/.gitignore
@@ -152,4 +152,3 @@
 /x86-generic_out/
 /xcodebuild
 
-!*.sha1