r325288: Changed OBJDIR paths /usr/obj[/amd64.amd64]/usr/src -> /usr/obj/usr/src/amd64.amd64/ (always target now)

FYI after r325288 the OBJDIR path used has changed to:
    MAKEOBJDIRPREFIX/SRCTOP/TARGET.TARGET_ARCH/RELDIR.

Meaning something like this:
    /usr/obj/usr/src/amd64.amd64/bin/sh

This pattern is used for cross, native, and sub-directory builds.
You can try moving your old object directories to the new paths or just
remove them.  META_MODE users may not rename the old directories, they
need to just be removed due to changed build commands due to use of
absolute OBJDIRS in the build (which I have opened review D12839 to
address later).

This can be disabled with WITHOUT_UNIFIED_OBJDIR=yes in
/etc/src-env.conf (not /etc/src.conf), but the option is planned to be
removed for 12.0 release.

-- 
Regards,
Bryan Drewery