MFC r268993, r268893, r268994, plus partial r264070, r264082

Fix C++ exception handling for ARM EABI.

Just the part of r264070 that creates the FBSD_1.4 namespace in libc
is hand-applied, and then r264082 which creates the Versions.def entry
is MFC'd.

MFC r258017, r258429, r258748, r258817:

Merge updates from FSF pre4.3 GCC inspired on Apple's gcc:

Updates to libiberty and mangling.
New align attribute.
Merge Apple updates to libstdc++.

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Make libsupc++'s __cxa_call_terminate() prototype consistent with the
definition.

Submitted by: dt71@gmx.com
MFC after: 3 days

Allow the unwind functions int libgcc_s to interact correctly with libthr.

_Unwind_ForcedUnwind in libgcc_s takes as one of it's parameters a stop
function to tell it when to stop unwinding. One of the stop function's
parameters is a _Unwind_Exception_Class. On most architectures this is an
int64_t, however on ARM EABI the gcc developers have made this a char array
with 8 items. While both of these take the same space they are passed into
the stop function differently, an int64_t is passed in in registers r2 and
r3, while the char[8] is passed in as a pointer to the first item in
register r2.

Because libthr expects the value to be an int64_t we would get incorrect
results when it passes a function that take an int64_t but libgcc passes in
a pointer to a char array including crashing.

The fix is to update libgcc_s to make it pass an int64_t to the stop
function and to libstdc++ as it expects _Unwind_Exception_Class to be an
array.

Fix a number of other clang warnings in libstdc++, which could appear
when building other C++ software with it. Also fix one actual bug in
libsupc++, which was exposed by such a warning. This latter fix is the
only functional change.

MFC after: 1 week

Undo the earlier revert of the ABI change in libsupc++. On further discussion,
posting an errata notice with 9.1 is the less painful solution.

Approved by: dim (mentor)

Revert ABI breakage in libsupc++.

Unfortunately, the ABI was broken upstream for the 4.2 release, which we
imported. We then shipped the broken version for several years and certain
ports (e.g. libobjc2) depend on it, so we're stuck with it for now...

We should revisit this for 10.0, since we're allowed to break the ABI then, but
until then we should keep the ABI we shipped with 8.x and 9.x.

Reviewed by: kan
Approved by: dim (mentor)
MFC after: 1 week

Update libstdc++ with small updates from the latest rev. (135556)
from the gcc 4.2 branch.
The libraries in the gcc-4_2-branch remained under the LGPLv2.

The changes can be reproduced with the following command:

svn diff svn://gcc.gnu.org/svn/gcc/branches/gcc-4_2-branch/libstdc++-v3
-r 127959:135556

Reviewed by: mm
Approved by: jhb (mentor)
MFC after: 2 weeks

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