Switch nacl-clang back to gas in SCons

Also re-enable nacl_clang tests which were disabled because of assembler
issues.

R=jvoung@chromium.org
BUG= https://code.google.com/p/nativeclient/issues/detail?id=3966
BUG= https://code.google.com/p/nativeclient/issues/detail?id=3969

Review URL: https://codereview.chromium.org/778483002

git-svn-id: svn://svn.chromium.org/native_client/trunk/src/native_client/site_scons@14164 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2
diff --git a/site_tools/naclsdk.py b/site_tools/naclsdk.py
index 441fa43..f4a8203 100755
--- a/site_tools/naclsdk.py
+++ b/site_tools/naclsdk.py
@@ -101,12 +101,6 @@
 
   cc = 'clang' if env.Bit('nacl_clang') else 'gcc'
   cxx = 'clang++' if env.Bit('nacl_clang') else 'g++'
-  # Eventually nacl-clang will default to -no-integrated-as but for now we have
-  # to use the integrated as for compilation because of
-  # https://code.google.com/p/nativeclient/issues/detail?id=3966
-  # However clang's as' support of some of the nacl syntax is incomplete, so for
-  # now use binutils as for our asm files.
-  as_flags = '-no-integrated-as' if env.Bit('nacl_clang') else []
 
   env.Replace(# Replace header and lib paths.
               # where to put nacl extra sdk headers
@@ -148,7 +142,7 @@
                        '-pedantic',
                        '-D__linux__',
                        ],
-              ASFLAGS=as_flags,
+              ASFLAGS=[],
               )
 
   # NaClSdk environment seems to be inherited from the host environment.