Fix fetching VS install path.

Author: grafikrobot

src/tools/clang-win.jam

@@ -140,7 +140,7 @@ rule init ( version ? : command * : options * )
             local vswhere = [ os.environ "ProgramFiles(x86)" ] ;
             vswhere ?= [ os.environ "ProgramFiles" ] ;
             vswhere = "$(vswhere)/Microsoft Visual Studio/Installer/vswhere.exe" ;
-            local vspath = [ SHELL "\"$(vswhere)\" -latest -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64" ] ;
+            local vspath = [ SHELL "\"$(vswhere)\" -latest -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath" ] ;
             .notice "$(arch)-$(addr):" "using VS tools in '$(vspath)'" ;
             local msvcpath = [ path.glob [ path.make "$(vspath)\\VC\\Tools\\MSVC" ] : * ] ;
             msvcpath = [ path.glob "$(msvcpath[-1])/bin" : Host* ] ;