Support msbuild.rsp in %USERPROFILE% directory

I used to launch an elevated notepad to change the msbuild.rsp file in the PF32\msbuild directory after installing VS to set a bunch of switches. But now msbuild is part of VS2017 and I update it frequently, and each time msbuild updates, the .rsp file is reset. This makes it much more frustrating to keep the file current.

I shouldn't have to elevate anyway. MSBuild.exe already searches two locations (the project directory and the installation directory) for .rsp files. Can we add the %USERPROFILE% directory as another?