Add support for CallKind::kCallOnMainAndSlowPath

Some of the intrinsics call on both the main and slowpath. This patch
adds support for such a CallKind and marks the intrinsics accordingly.

This will be exercised by a later patch that refactors all the runtime
calls to use InvokeRuntime().

Please note that without this patch, the calls to ValidateInvokeRuntime()
exercised by the following patches would fail.

Change-Id: I450571b8b47280a004b714996189ba6db13fb57d