How to build profiled libraries on RELENG_7?

[Lenar Tukhvatullin]

I need profiled versions of system libraries.

I put WITHOUT_PROFILE=NO in /etc/src.conf (/etc/make.conf not present)

With fresh source tree (RELENG_7 cvsup'ed today) i do:
make buildworld && make DESTDIR=/usr/test installworld

but can't find profiled libraries in /usr/test/usr/lib (libc_p.* for example)

How to build profiled libraries correctly?