Fix fruit_makefile

[jrwrigh]

Previous functionality would simply create a file in the home directory called lib.

Instead, the desired functionality is to place libfruit.so into the directory called lib.

[acroucher]

With the default values of $LIB and $INSTALL_DIR in the makefile, it is just doing cp libfruit.so ~/lib.

If you don't actually have a ~/lib directory, I guess it would create a file called lib in your home directory, as you reported.

It's assumed that the user will check that $INSTALL_DIR in the makefile is set to the appropriate directory for their system, and alter that if necessary.