Punch the --pnacl-allow-exceptions through from pnacl-driver/ld to translate.
Punch the --pnacl-allow-exceptions through from pnacl-driver/ld to translate.

This is for the all-the-way-to-native mode:
"pnacl-clang++ -arch x86-64 ... -o blah.nexe"
(instead of without -arch and -o blah.pexe).
Otherwise the native link step will fail because it was not
aware of --pnacl-allow-exceptions.

Also fix the behavior of -translate-fast if given to pnacl-ld w/
-arch ... -o blah.nexe.  Previously it was clobbering all of the
TRANSLATE_FLAGS with env.set(), when it should just env.append().

BUG=http://code.google.com/p/nativeclient/issues/detail?id=3069
TEST=./scons bitcode=1 pnacl_generate_pexe=0 toolchain_tests
R=eliben@chromium.org

Review URL: https://codereview.chromium.org/14556014

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@11284 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client