[FreeBSD] man pthread

thread programming てものはできない、しないんだけど。
libc_rの記述が無くなってたことに気づいた。

6.2-RELEASE:
(snip)
LIBRARY
POSIX Threads Library (libpthread, -lpthread)
1:1 Threading Library (libthr, -lthr)
Reentrant C Library (libc_r, -lc_r)
(snip)
INSTALLATION
The current FreeBSD POSIX thread implementation is built in three
libraries, Reentrant C Library (libc_r, -lc_r), POSIX Threads Library
(libpthread, -lpthread), and 1:1 Threading Library (libthr, -lthr). They
contain both thread-safe versions of Standard C Library (libc, -lc) func-
tions and the thread functions. Threaded applications are linked with
one of these libraries.

7.0-CURRENT:
(snip)
LIBRARY
POSIX Threads Library (libpthread, -lpthread)
1:1 Threading Library (libthr, -lthr)
(snip)
INSTALLATION
The current FreeBSD POSIX thread implementation is built in two
libraries, POSIX Threads Library (libpthread, -lpthread), and 1:1
Threading Library (libthr, -lthr). They contain both thread-safe ver-
sions of Standard C Library (libc, -lc) functions and the thread func-
tions. Threaded applications are linked with one of these libraries.