vim-patch:9.1.0196: filetype: support for gnuplot files is lacking (neovim#27972)

Problem:  filetype: support for gnuplot files is lacking
Solution: Also detect *.gnuplot files
          (RobbiZ98)

closes: vim/vim#14243

vim/vim@3a6bd0c

Co-authored-by: RobbiZ98 <[email protected]>

Author: clason

Diff for: runtime/lua/vim/filetype.lua

@@ -466,6 +466,7 @@ local extension = {
   glsl = 'glsl',
   gn = 'gn',
   gni = 'gn',
+  gnuplot = 'gnuplot',
   gpi = 'gnuplot',
   go = 'go',
   gp = 'gp',
@@ -1304,7 +1305,6 @@ local filename = {
   ['.gnashpluginrc'] = 'gnash',
   gnashpluginrc = 'gnash',
   gnashrc = 'gnash',
-  ['.gnuplot'] = 'gnuplot',
   ['go.sum'] = 'gosum',
   ['go.work.sum'] = 'gosum',
   ['go.work'] = 'gowork',

Diff for: test/old/testdir/test_filetype.vim

@@ -273,7 +273,7 @@ func s:GetFilenameChecks() abort
     \ 'glsl': ['file.glsl'],
     \ 'gn': ['file.gn', 'file.gni'],
     \ 'gnash': ['gnashrc', '.gnashrc', 'gnashpluginrc', '.gnashpluginrc'],
-    \ 'gnuplot': ['file.gpi', '.gnuplot'],
+    \ 'gnuplot': ['file.gpi', '.gnuplot', 'file.gnuplot'],
     \ 'go': ['file.go'],
     \ 'gomod': ['go.mod'],
     \ 'gosum': ['go.sum', 'go.work.sum'],