Thrift: Fix thrift.vim.

Summary:
thrift.vim has not been deleting its HiLink command.
This causes you to get a (recoverable) error every time you
open a C++ or PHP file after opening a thrift file.
This change deletes the HiLink command, preventing this error.

Reviewed By: martin

Test Plan:
Opened a thrift file, then opened a C++ file in the same session.
Both were highlighted properly.

Revert Plan: ok


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665194 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/thrift.vim b/thrift.vim
index 11da424..d81be13 100644
--- a/thrift.vim
+++ b/thrift.vim
@@ -66,6 +66,8 @@
   HiLink thriftNumber Number
   HiLink thriftSpecial Special
   HiLink thriftStructure Structure
+
+  delcommand HiLink
 endif
 
 let b:currenct_syntax = "thrift"