Merge pull request swiftlang#53 from benlangmuir/trfs

[test] Fix toolchain registry test to use in-memory file-system for search

Author: benlangmuir

Tests/SKCoreTests/ToolchainRegistryTests.swift

@@ -85,7 +85,7 @@ final class ToolchainRegistryTests: XCTestCase {
     XCTAssertNil(tr1.default)
     XCTAssert(tr1.toolchains.isEmpty)
 
-    tr1.scanForToolchains(xcode: xcodeDeveloper)
+    tr1.scanForToolchains(xcode: xcodeDeveloper, fs)
 
     XCTAssertEqual(tr1.default?.identifier, ToolchainRegistry.darwinDefaultToolchainIdentifier)
     XCTAssertEqual(tr1.default?.path, toolchains.appending(component: "XcodeDefault.xctoolchain"))