Add tests for C++11's std::rethrow_exception() (dependent exceptions)

Add tests for C++11's std::rethrow_exception() (dependent exceptions)

The first two tests added here test for bugs in eh_pnacl.cc (PNaCl
SJLJ EH support) in libsupc++, for which I've committed fixes.  The
third test tests for a potential bug but I've never seen it fail with
libsupc++.

All three tests passed first time with my SJLJ EH change for
libcxxabi, which is because libcxxabi's __cxa_exception and
__cxa_dependent_exception have matching layouts (with an exceptionType
field at the same offset), unlike in libsupc++.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3696
TEST=run_eh_throw_tests_sjlj_test

Committed: https://src.chromium.org/viewvc/native_client?view=rev&revision=12473

[Derek Schuff, 2013-12-02 21:55:55]

lgtm

[Mark Seaborn, 2013-12-03 03:40:13]

I've tweaked this to use
CXXFLAGS=['-std=gnu++11']
instead of
CCFLAGS=['-std=c++11']
because the latter breaks .c files and eh_floating_point.cc's use of M_PI_2
(non-ANSI).

[Mark Seaborn, 2013-12-03 03:42:30]

Committed patchset #4 manually as r12473 (presubmit successful).