[perl #130776] Environment variables are case insensitive on Windows

[via RT]

# New Ticket Created by  A. Sinan Unur 
# Please include the string:  [perl #130776]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=130776 >


$ echo %windir%
C:\WINDOWS

$ echo %WINDIR%
C:\WINDOWS

$ c:\opt\perl6-mingw\bin\perl6 -e "say %*ENV<WINDIR>"
(Any)

$ c:\opt\perl6-mingw\bin\perl6 -e "say %*ENV<windir>"
C:\WINDOWS

$ c:\opt\perl6-mingw\bin\perl6 -v
This is Rakudo version 2017.01 built on MoarVM version 2017.01
implementing Perl 6.c.

Both %*ENV<WINDIR> and %*ENV<windir> (as well as, e.g., %*ENV<WinDir>
etc) should return 'C:\WINDOWS'.

-- Sinan