Patch for make realclean

[Harald Fernengel]

Hello,

according to Paul Rohr's modification in
abi/src/config/require/unix/Makefile (which didn't work well for me)
I updated /abi/src/Makefile so a "make realclean" (in /abi/abi) now
really does what it states: Make everything clean. This includes
cleaning the libraries (libiconv, wv) so after a "make realclean"
you can copy the source from Windows to BeOS to Unix to QNX and
recompile it without problems.

Harry

realclean.patch