FreeBSD_HEAD_amd64_gcc4.9 - Build #631 - Fixed

FreeBSD_HEAD_amd64_gcc4.9 - Build #631 - Fixed:

Build information: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/631/
Full change log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/631/changes
Full build log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/631/console

Change summaries:

289076 by kan:
Add definitions for MIPS TLS relocations to elftoolchain.

This makes our readelf more useful when looking for TLS-related
issues.

289075 by kan:
Remove some trailing space.

289074 by emaste:
addr2line: initialize die to NULL

GCC on MIPS produced a 'may be used uninitialized' warning after
r289071.

Reported by:	sbruno
Pointy hat to:	emaste

289073 by dim:
Remove empty line again from libc++'s iostream.cpp.  This was used to
force updates to this file, so it will be rebuilt by the fixed clang
from r289072.

289072 by dim:
Temporarily revert upstream llvm trunk r240144 (by Michael Zolotukhin):

  [SLP] Vectorize for all-constant entries.

This should fix libc++'s iostream initialization SIGBUSing on amd64,
whenever the global cout symbol is not aligned to 16 bytes.

Some further explanation: libc++'s iostream.cpp contains the definitions
of std::cout, std::cerr and so on.  These global objects are effectively
declared with an alignment of 8 bytes.  When an executable is linked
against libc++.so, it can sometimes get a copy of the global object,
which is then at the same alignment.

However, with clang 3.7.0, the initialization of these global objects
will incorrectly use SSE instructions (e.g. movdqa), whenever the
optimization level is high enough, and SSE is enabled, such as on amd64.
When any of these objects is not aligned to 16 bytes, this will result
in a SIGBUS during iostream initialization.  In contrast, clang 3.6.x
and earlier took the 8 byte alignment into consideration, and avoided
SSE for those particular operations.

After bisecting of upstream changes, I found that the above revision
caused the change of this behavior, so I am reverting it now as a
workaround, while a discussion and test case is being prepared for
upstream.

289071 by emaste:
Update to ELF Tool Chain r3250

Highlights (not already in the FreeBSD tree):
  - addr2line: Fixed multiple memory leaks related to DIE allocation
  - readelf: improve sh_link validation
  - various man page improvements

Sponsored by:	The FreeBSD Foundation

289070 by emaste:
Add .gnu.versym VERSYM_HIDDEN flag and related mask

MFC after:	1 week
Sponsored by:	The FreeBSD Foundation