By default, the source distribution of cppunit is installed under /usr/local. When you run autoreconf -if, you get an error like this:
This is because cppunit.m4 is installed under /usr/local/share/aclocal, but aclocal only looks at /usr/share/aclocal-$VERSION and /usr/share/aclocal assuming it was configured with --prefix=/usr. There are 3 ways to specify additional paths.
1. Set ACLOCAL.
2. Set ACLOCAL_PATH.
3. Set ACLOCAL_FLAGS.
Apparently older versions of autoreconf don't respect ACLOCAL_PATH or ACLOCAL_FLAGS, so using ACLOCAL is probably the best way to fix it. I'll update src/c/README to document this.