[swift_build_support] Fix crash in FreeBSD toolchain.

utils/swift_build_support/swift_build_support/toolchain.py

@@ -147,7 +147,7 @@ def __init__(self):
         super(FreeBSD, self).__init__(suffixes)
 
     @cache_util.reify
-    def _release_date():
+    def _release_date(self):
         """Return the release date for FreeBSD operating system on this host.
         If the release date cannot be ascertained, return None.
         """

utils/swift_build_support/tests/test_toolchain.py

@@ -12,6 +12,7 @@
 import os
 import unittest
 
+from swift_build_support import toolchain
 from swift_build_support.toolchain import host_toolchain
 
 
@@ -110,6 +111,14 @@ def test_tools_llvm_suffix(self):
             if profdata_suffix is not None:
                 self.assertEqual(cc_suffix, profdata_suffix)
 
+    def test_toolchain_instances(self):
+        # Check that we can instantiate every toolchain, even if it isn't the
+        # current patform.
+        toolchain.MacOSX()
+        toolchain.Linux()
+        toolchain.FreeBSD()
+        toolchain.Cygwin()
+
 
 if __name__ == '__main__':
     unittest.main()