Update all of the autoconf files.

acx_pthread.m4 was added to detect pthreads.

make test/check now work.

m4/require_canonical.m4

@@ -0,0 +1,3 @@
+AC_DEFUN([REQUIRE_CANONICAL], [
+    AC_REQUIRE(AC_CANONICAL_HOST)_LT_SET_OPTION([LT_INIT],[win32-dll])
+])dnl REQUIRE_CANONICAL