We deprecated this module in commit v3.5.0-rc1~295^2
(CMakeForceCompiler: Deprecate this module and its macros, 2015-10-19)
in order to determine whether anyone still has use cases that require
it.  Indeed we still need to provide a way to work with toolchains that
cannot link binaries without special flags.  Remove the deprecation
warnings until we can provide an alternative to the module for this use
case.