patch 9.0.1478: filetypes for *.v files not detected properly

Problem:    Filetypes for *.v files not detected properly.
Solution:   Use the file contents to detect the filetype. (Turiiya,
            closes #12281)
diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index f399f1b..8518770 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -646,7 +646,6 @@
     \ 'vdmrt': ['file.vdmrt'],
     \ 'vdmsl': ['file.vdm', 'file.vdmsl'],
     \ 'vera': ['file.vr', 'file.vri', 'file.vrh'],
-    \ 'verilog': ['file.v'],
     \ 'verilogams': ['file.va', 'file.vams'],
     \ 'vgrindefs': ['vgrindefs'],
     \ 'vhdl': ['file.hdl', 'file.vhd', 'file.vhdl', 'file.vbe', 'file.vst', 'file.vhdl_123', 'file.vho', 'some.vhdl_1', 'some.vhdl_1-file'],
@@ -1771,6 +1770,27 @@
   filetype off
 endfunc
 
+func Test_v_file()
+  filetype on
+
+  call writefile(['module tb; // Looks like a Verilog'], 'Xfile.v', 'D')
+  split Xfile.v
+  call assert_equal('verilog', &filetype)
+  bwipe!
+
+  call writefile(['module main'], 'Xfile.v')
+  split Xfile.v
+  call assert_equal('v', &filetype)
+  bwipe!
+
+  call writefile(['Definition x := 10.  (*'], 'Xfile.v')
+  split Xfile.v
+  call assert_equal('coq', &filetype)
+  bwipe!
+
+  filetype off
+endfunc
+
 func Test_xpm_file()
   filetype on
 
diff --git a/src/version.c b/src/version.c
index c94a503..0df4436 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1478,
+/**/
     1477,
 /**/
     1476,