Assuming your C interfaces are appropriately wrapped for C++, it is
unnecessary to force the fakes to be declared extern "C", and doing so
causes any functions declared with C++ linkage to be impossible to fake
due to the conflicting linkage declarations.
Added the use of the $(MAKE) variable to support 'gnumake'.
Fixed an issue with some make compile rule and the -o option.
All targets are removed from the build directory when running 'make clean'.
