Along with an obsolete change to default.c it is in Patch.old if you care. This uses gcc. This uses gcc. Unfortunately, compiling with the optimizer causes it to dump core. All bugs reported for previous test releases have been fixed.
Some bugs surely remain.
This should compile the program in the current directory. One area that is often a problem in configuration and porting is the code to check the system's current load average. See the file NEWS for what has changed since previous releases. GNU Make is fully documented in make.texinfo. GNU Make is free software.