Move test for whitespace stripping out of function.

Rather than have the function call be a noop, which is misleading and a waste of
resources, this commit simply moves the conditional test up to the call site. If
g:spf13_keep_trailing_whitespace exists then we simply don't call the Strip()
function. This way Strip() can just do its job when called. I, for example, have
<leader>ws bound to this function and call it manually when needed. Hiding the
conditional inside the function broke that.

Author: johntyree

.vimrc

@@ -233,7 +233,10 @@
     set pastetoggle=<F12>           " pastetoggle (sane indentation on pastes)
     "set comments=sl:/*,mb:*,elx:*/  " auto format comment blocks
     " Remove trailing whitespaces and ^M chars
-    autocmd FileType c,cpp,java,go,php,javascript,python,twig,xml,yml autocmd BufWritePre <buffer> call StripTrailingWhitespace()
+    " To disable the stripping of whitespace, add the following to your
+    " .vimrc.before.local file:
+    "   let g:spf13_keep_trailing_whitespace = 1
+    autocmd FileType c,cpp,java,go,php,javascript,python,twig,xml,yml autocmd BufWritePre <buffer> if !exists('g:spf13_keep_trailing_whitespace') | call StripTrailingWhitespace() | endif
     autocmd FileType go autocmd BufWritePre <buffer> Fmt
     autocmd BufNewFile,BufRead *.html.twig set filetype=html.twig
     autocmd FileType haskell setlocal expandtab shiftwidth=2 softtabstop=2
@@ -890,20 +893,15 @@
 
     " Strip whitespace {
     function! StripTrailingWhitespace()
-        " To disable the stripping of whitespace, add the following to your
-        " .vimrc.before.local file:
-        "   let g:spf13_keep_trailing_whitespace = 1
-        if !exists('g:spf13_keep_trailing_whitespace')
-            " Preparation: save last search, and cursor position.
-            let _s=@/
-            let l = line(".")
-            let c = col(".")
-            " do the business:
-            %s/\s\+$//e
-            " clean up: restore previous search history, and cursor position
-            let @/=_s
-            call cursor(l, c)
-        endif
+        " Preparation: save last search, and cursor position.
+        let _s=@/
+        let l = line(".")
+        let c = col(".")
+        " do the business:
+        %s/\s\+$//e
+        " clean up: restore previous search history, and cursor position
+        let @/=_s
+        call cursor(l, c)
     endfunction
     " }