in function `xs_init':
/home/jv/tmp/aaa.c:28: undefined reference to `PL_thr_key'
/bin/ld: /home/jv/tmp/aaa.c:28: undefined reference to `pthread_getspecific'
/bin/ld: /home/jv/tmp/aaa.c:28: undefined reference to `Perl_newXS'