base-files: preserve PATH preset by environment

This delta aligns the value of `PATH` variable with other
shells/distros, which in their default configuration preserve
(append) the old value.
For instance: https://src.fedoraproject.org/rpms/bash/blob/master/f/dot-bashrc#_9.

In order to exercise interoperability with Win32 applications
in WSL, the subsystem process injects Windows environment's
PATH to the Linux OS, which in this case gets lost.

closes #6233

Co-authored-by: maxice8 <thinkabit.ukim@gmail.com>

srcpkgs/base-files/files/profile

@@ -2,8 +2,24 @@
 
 # System wide environment and startup programs.
 
+appendpath () {
+    case ":$PATH:" in
+        *:"$1":*)
+            ;;
+        *)
+            PATH="${PATH:+$PATH:}$1"
+    esac
+}
+
 # Set our default path (/usr/sbin:/sbin:/bin included for non-Void chroots)
-PATH="/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin"
+appendpath '/usr/local/sbin'
+appendpath '/usr/local/bin'
+appendpath '/usr/bin'
+appendpath '/usr/sbin'
+appendpath '/sbin'
+appendpath '/bin'
+unset appendpath
+
 export PATH
 
 # Set default umask

srcpkgs/base-files/template

@@ -1,7 +1,7 @@
 # Template file for 'base-files'
 pkgname=base-files
 version=0.140
-revision=2
+revision=3
 bootstrap=yes
 depends="xbps-triggers"
 short_desc="Void Linux base system files"