[test-suite] Add CMake option to use host-timeit

[mcrosier]

Summary

This change causes lit to use the host-compiled timeit when not remoting
into another host to run the test suite. timeit-target is intended to be
used on a host with the target architecture if cross-compiling, we
should always use timeit on the build host.

This is most important for cross-compiling and running under an
emulator, as timeit wraps around any run-under scripts given to lit.

[MatzeB]

What about we avoid an extra configuration flag and just always use timeit except when remote_host is set? Something like this:

timeit = "%s/tools/timeit" % config.test_source_root # move upwards
# ...
if config.remote_host:
    timeit = "%s/tools/timeit-target" % config.test_source_root

[mcrosier]

Use Matthis' suggestion.. Thanks!

[MatzeB]

Nitpick: You could have moved the timeit assignment a bit upwards to reuse the existing "if config.remote_host:"

In any way LGTM.

[mcrosier]

Address Matthias' nit.

[mcrosier]

Committed in r256944.

lit.cfg

     runsafely_prefix = [ runsafely ]
     if workdir is not None:
         runsafely_prefix += [ "-d", workdir ]
+    timeit = "%s/tools/timeit" % config.test_source_root
     if config.remote_host:
+        timeit = "%s/tools/timeit-target" % config.test_source_root
         runsafely_prefix += [ "-r", config.remote_host ]
         if config.remote_user:
             runsafely_prefix += [ "-l", config.remote_user ]

     else:
         if stdout is not None or stderr is not None:
             raise Exception("separate stdout/stderr redirection not possible with traditional output")
-    timeit = "%s/tools/timeit-target" % config.test_source_root
     timeout = "7200"
     if stdin is None:
         stdin = "/dev/null"