[refprop-headers] Build failed

[nitrogene]

Following resolution of #2166, I tried to install coolprop, but failed. There is an error in the portfile:

D:\Dev\vcpkg\ports\refprop-headers\portfile.cmake, on line 5 ${SOURCE_PATH} should be replaced by SOURCE_PATH (this is the same issue than for #2166).

[ras0219-msft]

Thanks for reporting this! I've corrected it in refprop-headers as well as a full sweep of all other portfiles :)