Fix PR456:\

Tools and libraries will be built into $(BUILD_OBJ_ROOT)/$(BuildMode)/bin and \
$(BUILD_OBJ_ROOT)/$(BuildMode)/lib, respectively. Furthermore, the example \
programs will go in $(BUILD_OBJ_ROOT)/$(BuildMode)/examples to keep them \
separate from the tools and hopefully out of the PATH. Install targets \
have not changed.

llvm-svn: 17953