tests/.gitignore: update for using Git's test infrastructure

Signed-off-by: John Keeping <john@keeping.me.uk>

.gitignore

@@ -1,5 +1,5 @@
 # Files I don't care to see in git-status/commit
-cgit
+/cgit
 cgit.conf
 CGIT-CFLAGS
 VERSION

tests/.gitignore

@@ -1,2 +1,2 @@
-trash
+trash\ directory.t*
-test-output.log
+test-results