test/ExecutionEngine: Clean up lit.local.cfg

Switch to using config.root.native_target to determine if tests are
supported.  This is a canonical form of the arch from the target
triple.

Reviewed By: lhames, DavidSpickett

Differential Revision: https://reviews.llvm.org/D110788

Author: tstellar

llvm/test/ExecutionEngine/lit.local.cfg

@@ -1,18 +1,4 @@
-if config.root.host_arch in ['Sparc', 'PowerPC', 'AArch64', 'ARM64', 'SystemZ']:
-    config.unsupported = True
-
-# CMake and autoconf diverge in naming or host_arch
-if 'powerpc64' in config.root.target_triple:
-    config.unsupported = True
-
-if 'aarch64' in config.root.target_triple \
-    or 'arm64' in config.root.target_triple:
-        config.unsupported = True
-
-if 'hexagon' in config.root.target_triple:
-    config.unsupported = True
-
-if 'sparc' in config.root.target_triple:
+if config.root.native_target in ['Sparc', 'PowerPC', 'AArch64', 'ARM64', 'SystemZ', 'Hexagon']:
     config.unsupported = True
 
 # ExecutionEngine tests are not expected to pass in a cross-compilation setup.