Add FreeBSD target_* support.

Author: landonf

test/lit.cfg

@@ -611,13 +611,20 @@ if run_vendor == 'apple':
         "%s ld -L%s" %
         (xcrun_prefix, os.path.join(test_resource_dir, config.target_sdk_name)))
 
-elif run_os == 'linux-gnu':
-    # Linux
-    lit_config.note("Testing Linux " + config.variant_triple)
+elif run_os == 'linux-gnu' or run_os.startswith('freebsd'):
+    # Linux/FreeBSD
+    if run_os == 'linux-gnu':
+        config.target_sdk_name = "linux"
+    elif run_os.startswith('freebsd'):
+        config.target_sdk_name = "freebsd"
+
+    lit_config.note("Testing " + config.target_sdk_name + " " +
+        config.variant_triple)
+
     config.target_object_format = "elf"
     config.target_runtime = "native"
     config.target_swift_autolink_extract = inferSwiftBinary("swift-autolink-extract")
-    config.target_sdk_name = "linux"
+
     config.target_build_swift = (
         '%s -target %s %s %s %s %s'
         % (config.swiftc, config.variant_triple, resource_dir_opt, mcp_opt,