Well, on my system (Ubuntu) at least this is not the case and renaming the files gets past the errors and on to actual build errors:

  runtime/cxx.cc:74:41: error: ‘operator new’ takes type ‘size_t’ (‘unsigned int’) as first parameter [-fpermissive]
  runtime/cxx.cc:84:43: error: ‘operator new’ takes type ‘size_t’ (‘unsigned int’) as first parameter [-fpermissive]
  make[1]: *** [runtime/cxx.o] Error 1

After renaming the Makefiles to fix the case, running make clean and then make all, I get the same error.

Is there a configure script or cmake or something? It looks like you might have to do something before `make all`

Nope, just a top level makefile and a readme that says to compile you only need to

    make all

make looks for [Mm]akefile if you run it with no arguments, but here it's being run recursively (or included). On OSX, filenames are case-insensitive, which could be a possible reason why it works for some people. On Linux, filenames are case sensitive.

That seems to be the case, since running file on one of the existing .o files says that they are Mach-O i386 objects. The readme doesn't mention OS X though, only Ubuntu