Before VS 2013 ToolsVersion contained a .NET version
number (e.g. "4.0"). Since VS 2013 ToolsVersion is the same as the
Visual Studio version number (e.g. "12.0"), which is also the default.
We always wrote "4.0" (except in one special case which used
"14.0"). This doesn't bother Visual Studio itself, but other tools
like PVS-Studio.
Remove the ToolsVersion attribute from generated VS projects for VS
2013 and newer.
Task-number: QTBUG-57694
Change-Id: I7a3bc4534c492e9540f6b968bee8a969980df63f
Reviewed-by: Jake Petroules <jake.petroules@qt.io>
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
88a02c4d63