Switch nacl-clang back to gas in SCons

tests/signal_handler_single_step/nacl.scons

Index: tests/signal_handler_single_step/nacl.scons
diff --git a/tests/signal_handler_single_step/nacl.scons b/tests/signal_handler_single_step/nacl.scons
index 5792d35e72fce839f8ff8f8717d6622abd81e46a..3c794d64129290a9cc576e1f0907e35ebc324051 100644
--- a/tests/signal_handler_single_step/nacl.scons
+++ b/tests/signal_handler_single_step/nacl.scons
@@ -27,13 +27,6 @@ if env.Bit('host_windows'):
 # restore %cs to its saved value on return from a signal handler.
 if env.Bit('host_mac'):
   Return()
-# nacl-clang's integrated assembler expands "naclcall" to a sequence which
-# separates the push of the return address from the jump, and so breaks the
-# test's expectations for the stack pointer.
-# TODO(dschuff): re-enable this test after we switch to gas with nacl-clang
-# https://code.google.com/p/nativeclient/issues/detail?id=3966
-if env.Bit('nacl_clang'):
-  Return()
 
 if env.Bit('build_x86'):
   step_test_guest = env.ComponentProgram(