runtime(zip): remove test for fnameescape

Problem:  zip plugin tests for fnameescape() function
Solution: Remove the check, fnameescape() has been available since
          7.1.299, it should nowadays always be available

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/autoload/zip.vim b/runtime/autoload/zip.vim
index d22e2e0..cf70135 100644
--- a/runtime/autoload/zip.vim
+++ b/runtime/autoload/zip.vim
@@ -87,12 +87,6 @@
   set report=10
 
   " sanity checks
-  if !exists("*fnameescape")
-   if &verbose > 1
-    echoerr "the zip plugin is not available (your vim doesn't support fnameescape())"
-   endif
-   return
-  endif
   if !executable(g:zip_unzipcmd)
    redraw!
    echohl Error | echomsg "***error*** (zip#Browse) unzip not available on your system"