hadrian test: in-tree arguments don't match out-of-tree arguments

When the tree is configured with --enable-unregisterised, testing with hadrian/build test will produce a warning message as follows:

Hadrian assertion failure: in-tree arguments don't match out-of-tree arguments.
Please report this bug on the GHC issue tracker. Continuing with in-tree arguments.
in-tree arguments:
TestCompilerArgs {hasDynamicRts = True, hasThreadedRts = True, hasDynamic = True, leadingUnderscore = False, withNativeCodeGen = True, withInterpreter = True, unregisterised = True, withSMP = False, debugAssertions = False, profiled = False, os = "linux", arch = "x86_64", platform = "x86_64-unknown-linux", wordsize = "64", libdir = "/workspace/ghc/_build/stage1/lib", have_llvm = True, rtsLinker = True, pkgConfCacheFile = "/workspace/ghc/_build/stage1/lib/package.conf.d/package.cache"}
out-of-tree arguments:
TestCompilerArgs {hasDynamicRts = True, hasThreadedRts = True, hasDynamic = True, leadingUnderscore = False, withNativeCodeGen = False, withInterpreter = True, unregisterised = True, withSMP = False, debugAssertions = False, profiled = False, os = "linux", arch = "x86_64", platform = "x86_64-unknown-linux", wordsize = "64", libdir = "/workspace/ghc/_build/stage1/lib", have_llvm = True, rtsLinker = True, pkgConfCacheFile = "/workspace/ghc/_build/stage1/lib/package.conf.d/package.cache"}

It seems the in-tree arguments incorrectly assumes withNativeCodeGen = True. This will make test ways like optasm get run where they shouldn't in unregisterised ghc.