patch 8.0.1527: screen dump test fails on MS-Windows

Problem:    Screen dump test fails on MS-Windows.
Solution:   Skip dump test on MS-Windows for now.
diff --git a/src/testdir/test_syntax.vim b/src/testdir/test_syntax.vim
index e60bb52..554ff16 100644
--- a/src/testdir/test_syntax.vim
+++ b/src/testdir/test_syntax.vim
@@ -526,7 +526,8 @@
 
 " Check highlighting for a small piece of C code with a screen dump.
 func Test_syntax_c()
-  if !has('terminal')
+  " Need to be able to run terminal Vim with 256 colors.
+  if !has('terminal') || has('win32')
     return
   endif
   call writefile([