patch 8.1.2131: MSVC tests fail

Problem:    MSVC tests fail.
Solution:   Replace backslashes with slashes.
diff --git a/src/testdir/test_compiler.vim b/src/testdir/test_compiler.vim
index 06522d7..6bb6027 100644
--- a/src/testdir/test_compiler.vim
+++ b/src/testdir/test_compiler.vim
@@ -38,10 +38,11 @@
 endfunc
 
 func Test_compiler_without_arg()
-  let a=split(execute('compiler'))
-  call assert_match($VIMRUNTIME .. '/compiler/ant.vim$',   a[0])
-  call assert_match($VIMRUNTIME .. '/compiler/bcc.vim$',   a[1])
-  call assert_match($VIMRUNTIME .. '/compiler/xmlwf.vim$', a[-1])
+  let runtime = substitute($VIMRUNTIME, '\\', '/', 'g')
+  let a = split(execute('compiler'))
+  call assert_match(runtime .. '/compiler/ant.vim$',   a[0])
+  call assert_match(runtime .. '/compiler/bcc.vim$',   a[1])
+  call assert_match(runtime .. '/compiler/xmlwf.vim$', a[-1])
 endfunc
 
 func Test_compiler_completion()
diff --git a/src/testdir/test_spell.vim b/src/testdir/test_spell.vim
index 5231266..9cbfaa5 100644
--- a/src/testdir/test_spell.vim
+++ b/src/testdir/test_spell.vim
@@ -128,20 +128,21 @@
 
 func Test_spellinfo()
   new
+  let runtime = substitute($VIMRUNTIME, '\\', '/', 'g')
 
   set enc=latin1 spell spelllang=en
-  call assert_match("^\nfile: " .. $VIMRUNTIME .. "/spell/en.latin1.spl\n$", execute('spellinfo'))
+  call assert_match("^\nfile: " .. runtime .. "/spell/en.latin1.spl\n$", execute('spellinfo'))
 
   set enc=cp1250 spell spelllang=en
-  call assert_match("^\nfile: " .. $VIMRUNTIME .. "/spell/en.ascii.spl\n$", execute('spellinfo'))
+  call assert_match("^\nfile: " .. runtime .. "/spell/en.ascii.spl\n$", execute('spellinfo'))
 
   set enc=utf-8 spell spelllang=en
-  call assert_match("^\nfile: " .. $VIMRUNTIME .. "/spell/en.utf-8.spl\n$", execute('spellinfo'))
+  call assert_match("^\nfile: " .. runtime .. "/spell/en.utf-8.spl\n$", execute('spellinfo'))
 
   set enc=latin1 spell spelllang=en_us,en_nz
   call assert_match("^\n" .
-                 \  "file: " .. $VIMRUNTIME .. "/spell/en.latin1.spl\n" .
-                 \  "file: " .. $VIMRUNTIME .. "/spell/en.latin1.spl\n$", execute('spellinfo'))
+                 \  "file: " .. runtime .. "/spell/en.latin1.spl\n" .
+                 \  "file: " .. runtime.. "/spell/en.latin1.spl\n$", execute('spellinfo'))
 
   set spell spelllang=
   call assert_fails('spellinfo', 'E756:')
diff --git a/src/version.c b/src/version.c
index a064648..2dc9f9b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2131,
+/**/
     2130,
 /**/
     2129,