Unconditionally link with libpthread (if available) to work around
a problem with segfault on dlclose()ing a driver that itself links
with libpthread.

(actually, it's the arts driver, which links with libarts which in
 turn links with libpthread)


git-svn-id: http://svn.xiph.org/trunk/ao@1368 0101bb08-14d6-0310-b084-bc0e0c8e3800

configure.in

@@ -73,6 +73,10 @@ dnl ==============================
 dnl Check for libraries
 dnl ==============================
 
+# we link to libpthread just in case one of our plugins does
+# in which case this is required to avoid problems on dlclose()
+AC_CHECK_LIB(pthread, pthread_kill)
+
 dnl ==============================
 dnl Checks for header files
 dnl ==============================