runtime: Remove fallback :CompilerSet definition from compiler plugins

The :CompilerSet command was added in version Vim 6.4 which was released
twenty years ago.  Other runtime files do not support versions of that
vintage so it is reasonable to remove this fallback command definition
now.

closes: #14399

Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/compiler/modelsim_vcom.vim b/runtime/compiler/modelsim_vcom.vim
index 184b403..8c6b806 100644
--- a/runtime/compiler/modelsim_vcom.vim
+++ b/runtime/compiler/modelsim_vcom.vim
@@ -3,6 +3,7 @@
 " Maintainer:	Paul Baleme <pbaleme@mail.com>
 " Contributors: Enno Nagel
 " Last Change:	2024 Mar 29
+"		2024 Apr 03 by The Vim Project (removed :CompilerSet definition)
 " Thanks to:    allanherriman@hotmail.com
 
 if exists("current_compiler")
@@ -10,10 +11,6 @@
 endif
 let current_compiler = "modelsim_vcom"
 
-if exists(":CompilerSet") != 2		" older Vim always used :setlocal
-  command -nargs=* CompilerSet setlocal <args>
-endif
-
 CompilerSet makeprg=vcom
 
 "setlocal errorformat=\*\*\ %tRROR:\ %f(%l):\ %m,%tRROR:\ %f(%l):\ %m,%tARNING\[%*[0-9]\]:\ %f(%l):\ %m,\*\*\ %tRROR:\ %m,%tRROR:\ %m,%tARNING\[%*[0-9]\]:\ %m