Crypt the swapfile.
diff --git a/runtime/syntax/c.vim b/runtime/syntax/c.vim
index 9456212..a0b94ae 100644
--- a/runtime/syntax/c.vim
+++ b/runtime/syntax/c.vim
@@ -270,7 +270,7 @@
endif
" Accept %: for # (C99)
-syn region cPreCondit start="^\s*\(%:\|#\)\s*\(if\|ifdef\|ifndef\|elif\)\>" skip="\\$" end="$" contains=cComment,cCommentL,cCppString,cCharacter,cCppParen,cParenError,cNumbers,cCommentError,cSpaceError
+syn region cPreCondit start="^\s*\(%:\|#\)\s*\(if\|ifdef\|ifndef\|elif\)\>" skip="\\$" end="$" keepend contains=cComment,cCommentL,cCppString,cCharacter,cCppParen,cParenError,cNumbers,cCommentError,cSpaceError
syn match cPreCondit display "^\s*\(%:\|#\)\s*\(else\|endif\)\>"
if !exists("c_no_if0")
if !exists("c_no_if0_fold")