Runtime control per application

[Thomas Wolff]

Hi,
a recent patch in MSYS:
https://github.com/msys2/msys2-runtime/commit/cd4b539b367dc2a21041405cb52d3bf5dbf1a3be
supports finer-grained control about runtime behaviour as configured via 
MSYS/Cygwin environment.
Maybe it would be a good idea to patch cygwin upstream likewise.

Test case (here in Windows German language configuration):

MSYS:
 > xcopy
Unzulässige Parameteranzahl
0 Datei(en) kopiert
 > MSYS=disable_pcon xcopy
Unzul▒ssige Parameteranzahl
0 Datei(en) kopiert
 >

Cygwin:
 > xcopy
Unzulässige Parameteranzahl
0 Datei(en) kopiert
 > CYGWIN=disable_pcon xcopy
Unzulässige Parameteranzahl
0 Datei(en) kopiert
 > CYGWIN=disable_pcon sh -c xcopy
Unzul�ssige Parameteranzahl
0 Datei(en) kopiert
 >

In Cygwin, an additional shell is needed to make the $CYGWIN 
configuration effective, in MSYS now it works directly.
Question, being curious: How does this work at all? What system call of 
the shell makes the change effective?
Thomas