move s:uname() in with the rest of the functions - close to its usage

plugin/syntastic.vim

@@ -19,13 +19,6 @@ let g:loaded_syntastic_plugin = 1
 
 let s:running_windows = has("win16") || has("win32")
 
-function! s:uname()
-    if !exists('s:uname')
-        let s:uname = system('uname')
-    endif
-    return s:uname
-endfunction
-
 if !exists("g:syntastic_enable_signs")
     let g:syntastic_enable_signs = 1
 endif
@@ -493,6 +486,13 @@ function! s:OSSupportsShellpipeHack()
     return s:os_supports_shellpipe_hack
 endfunction
 
+function! s:uname()
+    if !exists('s:uname')
+        let s:uname = system('uname')
+    endif
+    return s:uname
+endfunction
+
 "check if a syntax checker exists for the given filetype - and attempt to
 "load one
 function! SyntasticCheckable(ft)