When matching configurations using CONF, normally this is treated as a pattern. However, if an exact match is found, this is exclusively used. This is to allow matching for e.g. linux-x64 and not matching linux-x64-debug, which is otherwise impossible.

To inform the user that this has happend, make prints

Using exact match for CONF=linux-x64 (other matches are possible)

even if no other matches are possible.