message: Use LLDB_LIB_DIR to locate the lldb binary
  The name seems to indicate otherwise, but dotest sets this variable to
  the dirname of the lldb executable. It should be independant of the current
  build type.
diff: LEVEL = ../../make
  SWIFT_OBJC_INTEROP := 1
  -LLDB=$(shell echo $(BUILDDIR)/../../../../[bC]*/lldb)
  +LLDB=$(shell echo $(LLDB_LIB_DIR)/lldb)
  # This Makefile overwrites the default rules.
  EXE := a.out
  