[develop2] Allow passing pathname to other conanfile.txt

[timwoj]

The develop2 branch appears to require you to have conanfile.py or conanfile.txt in the root of your project. We're only using conan on Windows, so we're storing our conanfile with some other Windows-specific build/CI files. It'd be nice to be able to pass a path to cmake/conan to specify where to look for the conanfile instead of fixing it to a specific location.

[li-dl]

It'd be nice to be able to pass a path to cmake/conan to specify where to look for the conanfile instead of fixing it to a specific location.

Seconded.

I see that @timwoj created a pull request for this (#605) that solved the issue by adding a CONAN_CONANFILE_TXT_PATH variable, but the source repo was deleted before the PR was reviewed.

Was the idea sound? Should I update the pull request and resubmit it?

[snakethatlovesstaticlibs]

+1, we have a number of lockfiles for different flavors of the build, and we want to specify which one should be used