link with pthread flags when checking for Berkeley DB thread support (ITS#2209)

[china@thewrittenword.com]

Full_Name: Albert Chin-A-Young
Version: 2.1.8
OS: Tru64 UNIX 5.1
URL: ftp://ftp.openldap.org/incoming/chinayoung-021126.3
Submission from: (NULL) (67.89.104.162)


If Berkeley DB has been linked with thread support, the thread flags detected in
the autoconf tests for OpenLDAP 2.1.8 should be used in the test for Berkeley DB
thread support. This is needed on Tru64 UNIX 5.1. Without this patch,
./configure errors with:
...
checking for db.h... yes
checking for Berkeley DB link (default)... no
checking for Berkeley DB link (-ldb4)... no
checking for Berkeley DB link (-ldb-4)... yes
checking for Berkeley DB thread support... 189687:./conftest: /sbin/loader:
Fatal Error: Reference to unresolvable symbol "pthread_mutexattr_init" in
"/opt/TWWfsw/libdb41/lib/libdb-4.1.so"
no
checking Berkeley DB version for BDB backend... yes
checking for tcpd.h... yes

Patch at:
  ftp://ftp.openldap.org/incoming/chinayoung-021126.3