runtime(ftplugin): allow to exec if curdir is in PATH

In case the current directory is present as valid $PATH entry, it is OK
to call the program from it, even if vim curdir is in that same
directory.

(Without that patch, for instance, you will not be able to open .zip
files while your current directory is /bin)

closes: #13027

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/ftplugin/perl.vim b/runtime/ftplugin/perl.vim
index edc7b96..4361097 100644
--- a/runtime/ftplugin/perl.vim
+++ b/runtime/ftplugin/perl.vim
@@ -55,7 +55,9 @@
 " Set this once, globally.
 if !exists("perlpath")
     " safety check: don't execute perl from current directory
-    if executable("perl") && fnamemodify(exepath("perl"), ":p:h") != getcwd()
+    let s:tmp_cwd = getcwd()
+    if executable("perl") && (fnamemodify(exepath("perl"), ":p:h") != s:tmp_cwd
+          \ || (index(split($PATH,has("win32")? ';' : ':'), s:tmp_cwd) != -1 && s:tmp_cwd != '.'))
       try
 	if &shellxquote != '"'
 	    let perlpath = system('perl -e "print join(q/,/,@INC)"')
@@ -71,6 +73,7 @@
 	" current directory and the directory of the current file.
 	let perlpath = ".,,"
     endif
+    unlet s:tmp_cwd
 endif
 
 " Append perlpath to the existing path value, if it is set.  Since we don't