patch 8.1.1593: filetype not detected for C++ header files without extension

Problem:    Filetype not detected for C++ header files without extension.
Solution:   Recognize the file by the Emacs file mode. (Dmitry Ilyin,
            closes #4593)
diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index 95fb62e..37d8ced 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -586,6 +586,8 @@
       \ 'cfengine': [['#!/path/cfengine']],
       \ 'erlang': [['#!/path/escript']],
       \ 'haskell': [['#!/path/haskell']],
+      \ 'cpp': [['// Standard iostream objects -*- C++ -*-'],
+      \         ['// -*- C++ -*-']],
       \ }
 
 func Test_script_detection()
diff --git a/src/version.c b/src/version.c
index 5514b4b..c25c1ff 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1593,
+/**/
     1592,
 /**/
     1591,