When logging, there is no such thing as overkill. That's why god gave us grep. The full, verbose output of the build log and of the tests is indispensable. Possibly, as dmake has just seen a new version, the version number of $Config{make} could be of interest too, especially as your focus is on non-MS Win32 Perl distributions.

I thinkt that MSVC also uses $ENV{INCLUDE} and $ENV{LIB} to indicate the include and library directories.

One thing of possible other interest could be the number of CPUs the machine has, just to track down potential race condition problems causing tests to fail - on Win32, this would be via $ENV{NUMBER_OF_PROCESSORS}, at least on Windows 2000 onwards.