Merge pull request #1764 from modocache/build-presets-xctest-ci

Author: swift-ci

utils/build-presets.ini

@@ -262,8 +262,9 @@ skip-test-watchos
 # build for iOS/tvOS.
 mixin-preset=buildbot_incremental_base
 
-# Build Foundation, then build and test XCTest.
-foundation
+# Build and test XCTest. On Linux, the build script is aware of the dependency
+# on Foundation, so that is built as well. On OS X, Foundation is built as part
+# of the XCTest Xcode project.
 xctest
 
 dash-dash