vim: Don't set foldmethod in the syntax file either

We shouldn't be setting any settings in the syntax file. Better to put
them in the ftplugin, where they won't be pulled in by :syn-include and
can be cleaned up when changing the filetype.

src/etc/vim/ftplugin/rust.vim

@@ -56,6 +56,16 @@ if exists("g:loaded_delimitMate")
 	let b:delimitMate_excluded_regions = delimitMate#Get("excluded_regions") . ',rustLifetimeCandidate,rustGenericLifetimeCandidate'
 endif
 
+if has("folding") && exists('g:rust_fold') && g:rust_fold != 0
+	let b:rust_set_foldmethod=1
+	setlocal foldmethod=syntax
+	if g:rust_fold == 2
+		setlocal foldlevel<
+	else
+		setlocal foldlevel=99
+	endif
+endif
+
 if has('conceal') && exists('g:rust_conceal')
 	let b:rust_set_conceallevel=1
 	setlocal conceallevel=2
@@ -108,6 +118,10 @@ let b:undo_ftplugin = "
 		\|else
 		  \|unlet! b:delimitMate_excluded_regions
 		\|endif
+		\|if exists('b:rust_set_foldmethod')
+		  \|setlocal foldmethod< foldlevel<
+		  \|unlet b:rust_set_foldmethod
+		\|endif
 		\|if exists('b:rust_set_conceallevel')
 		  \|setlocal conceallevel<
 		  \|unlet b:rust_set_conceallevel

src/etc/vim/syntax/rust.vim

@@ -11,17 +11,6 @@ elseif exists("b:current_syntax")
   finish
 endif
 
-" Fold settings {{{1
-
-if has("folding") && exists('g:rust_fold') && g:rust_fold != 0
-  setlocal foldmethod=syntax
-  if g:rust_fold == 2
-    setlocal foldlevel<
-  else
-    setlocal foldlevel=99
-  endif
-endif
-
 " Syntax definitions {{{1
 " Basic keywords {{{2
 syn keyword   rustConditional match if else