Fixed how the Makefile collects targets.
Fixed how the Makefile collects targets.

The Makefile was previously 'leaking' .cpp files into the CFILES
variable, causing some files to be compiled twice and leading to
duplicated symbols.

Now, CFILES (as well as its partner, OBJS) are built piecewise, avoiding
any duplication.

8l/SmallWM,8l/swm,8l/swm,8l/SmallWM