Disable pt recursion test

The platinum searcher is non-deterministic because it uses multiple threads in
its search. An ideal workaround for this problem would be to have an option in
pt that specifies the number of cores to use; a lot of tools have a -j option
like this.

Author: dkprice

tests/vimgrep.suite

@@ -28,7 +28,7 @@ recursion_ack.vim
 recursion_ag.vim
 recursion_findstr.vim
 recursion_grep.vim
-recursion_pt.vim
+# recursion_pt.vim # disabled; output is non-deterministic
 recursion_vimgrep.vim
 
 # simpleregex