[sil-ownership] Add a new preset buildbot,tools=RA,stdlib=RDA,sil-ownership for building swift on a buildbot with sil-ownership enabled.

rdar://28685236

Author: gottesmm

utils/build-presets.ini

@@ -258,6 +258,12 @@ skip-test-ios-host
 skip-test-tvos-host
 skip-test-watchos-host
 
+[preset: buildbot,tools=RA,stdlib=RDA,sil-ownership]
+mixin-preset=
+    buildbot,tools=RA,stdlib=RDA
+build-subdir=Ninja-ReleaseAssert+stdlib-RelWithDebInfo+sil-ownership
+enable-sil-ownership
+dash-dash
 
 #===------------------------------------------------------------------------===#
 # Incremental buildbots for Darwin OSes