patch 8.2.3587: compiler test fails with backslash file separator

Problem:    Compiler test fails with backslash file separator.
Solution:   Accept slash and backslash.

src/testdir/test_compiler.vim

@@ -22,7 +22,7 @@ func Test_compiler()
   call assert_fails('let g:current_compiler', 'E121:')
 
   let verbose_efm = execute('verbose set efm')
-  call assert_match('Last set from .*/compiler/perl.vim ', verbose_efm)
+  call assert_match('Last set from .*[/\\]compiler[/\\]perl.vim ', verbose_efm)
 
   call setline(1, ['#!/usr/bin/perl -w', 'use strict;', 'my $foo=1'])
   w!

src/version.c

@@ -757,6 +757,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3587,
 /**/
     3586,
 /**/