Add pthread '-mt' detection for Solaris 2.x (from -devel).

Still requires ac_cv_func_pthread_create=no workaround.

CHANGES

@@ -1,5 +1,11 @@
 OpenLDAP Change Log
 
+Changes included in OpenLDAP 1.2.1
+	CVS Tag: OPENLDAP_REL_ENG_1_2
+	Updated ctype and string generic headers.
+	Build environment
+		Added pthread '-mt' check for Solaris 2.x.
+
 Changes included in OpenLDAP 1.2
 	CVS Tag: OPENLDAP_REL_ENG_1_2_0
 	Fixed slapd/back-ldbm/cache entry lock assert bugs

configure.in

@@ -426,6 +426,7 @@ if test $ol_with_threads = auto -o $ol_with_threads = yes \
 		dnl 	pthread_create() with -pthread (FreeBSD/Digital Unix)
 		dnl 	pthread_create() with -pthreads (?)
 		dnl 	pthread_create() with -thread (?)
+		dnl 	pthread_create() with -mt (Solaris)
 		dnl
 		dnl Check pthread (final) libraries
 		dnl 	pthread_mutex_unlock() in -lpthread -lmach -lexc -lc_r (OSF/1)
@@ -529,6 +530,26 @@ if test $ol_with_threads = auto -o $ol_with_threads = yes \
 			fi
 		fi
 
+		if test $ol_link_threads = no ; then
+			dnl try -mt
+			AC_CACHE_CHECK([for pthread_create with -mt],
+				[ol_cv_thread_flag], [
+				dnl save the flags
+				save_LIBS="$LIBS"
+				LIBS="-mt $LIBS"
+				AC_TRY_LINK([char pthread_create();],
+					[pthread_create();],
+					[ol_cv_thread_flag=yes], [ol_cv_thread_flag=no])
+				dnl restore the LIBS
+				LIBS="$save_LIBS"
+			])
+
+			if test $ol_cv_thread_flag = yes ; then
+				LTHREAD_LIBS="$LTHREAD_LIBS -mt"
+				ol_link_threads=posix
+			fi
+		fi
+
 		if test $ol_link_threads = no ; then
 			dnl try DEC Threads -lpthread -lmach -lexc -lc_r
 			save_LIBS="$LIBS"