runtime(compilers): ensure compiler! sets global options (#14336)

Previously some options were only set locally by
&l:makeprg/errorformat

This suffices for :compiler (without a trailing bang)
but falls short for :compiler! that sets &g:makeprg/errorformat as
well

Also apply kind suggestions by @dkearns and @lifepillar 

Signed-off-by: Konfekt <Konfekt@users.noreply.github.com>
Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/compiler/powershell.vim

@@ -1,7 +1,8 @@
 " Vim compiler file
 " Compiler:	powershell
 " URL: https://github.com/PProvost/vim-ps1
-" Last Change: 2020 Mar 30
+" Contributors: Enno Nagel
+" Last Change: 2024 Mar 29
 
 if exists("current_compiler")
   finish
@@ -37,7 +38,7 @@ let g:ps1_efm_show_error_categories = get(g:, 'ps1_efm_show_error_categories', 0
 
 " Use absolute path because powershell requires explicit relative paths
 " (./file.ps1 is okay, but # expands to file.ps1)
-let &l:makeprg = g:ps1_makeprg_cmd .' %:p:S'
+let makeprg = g:ps1_makeprg_cmd .. ' %:p:S'
 
 " Parse file, line, char from callstacks:
 "     Write-Ouput : The term 'Write-Ouput' is not recognized as the name of a
@@ -50,6 +51,8 @@ let &l:makeprg = g:ps1_makeprg_cmd .' %:p:S'
 "         + CategoryInfo          : ObjectNotFound: (Write-Ouput:String) [], CommandNotFoundException
 "         + FullyQualifiedErrorId : CommandNotFoundException
 
+execute 'CompilerSet makeprg=' .. escape(makeprg, ' ')
+
 " Showing error in context with underlining.
 CompilerSet errorformat=%+G+%m
 " Error summary.