update-via-pacman: ensure that git.exe is in the PATH

The post-install script of `git-extra` (which we source manually)
assumes that the native `git.exe` is in the `PATH`. Let's make it so.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

update-via-pacman.ps1

@@ -23,10 +23,10 @@ function die {
 Set-Location $PSScriptRoot
 if (!$?) { die "Could not switch directory to $PSScriptRoot" }
 
-$env:PATH = "$(Get-Location)\usr\bin;" + $env:PATH
+$env:PATH = "$(Get-Location)\mingw64\bin;$(Get-Location)\usr\bin;" + $env:PATH
 
 # Set to MSYS mode
-$env:MSYSTEM = "MSYS"
+$env:MSYSTEM = "MINGW64"
 $env:MSYS2_PATH_TYPE = "minimal"
 
 # Create /var/log/ so that pacman.log is written