[buildbot, windows] The property LLDB_TEST_COMPILER is obsolete

[stella.stamenova]

Summary

This property no longer exists - it was replaced by LLDB_TEST_C_COMPILER and LLDB_TEST_CXX_COMPILER both of which default to the value that used to be passed in as a parameter.

[gkistanova]

LGTM

zorg/buildbot/builders/LLDBBuilder.py

f.addStep(RemoveDirectory(name='clean '+build_dir,
                 flunkOnFailure=False,
                 doStepIf=cleanBuildRequested
                 ))
 
     cmake_cmd = [
         "cmake", "-G", "Ninja", "../llvm",
         "-DCMAKE_BUILD_TYPE=" + config,
         "-DPYTHON_HOME=" + python_source_dir,
-        "-DCMAKE_INSTALL_PREFIX=../install",
-        "-DLLDB_TEST_COMPILER=\"%(builddir)s/bin/clang.exe\""
+        "-DCMAKE_INSTALL_PREFIX=../install"
         ]
     if extra_cmake_args:
         cmake_cmd += extra_cmake_args
     # Note: ShellCommand does not pass the params with special symbols right.
     # The " ".join is a workaround for this bug.
     f.addStep(ShellCommand(name="cmake-configure",
                            description=["cmake configure"],
                            command=WithProperties(" ".join(cmake_cmd)),