Darwin: Fix a copy/paste error that was introduced in r12458
Fill in missing signal handling macros for amd64-darwin.
Keep the stack properly 16-aligned when delivering signals on
amd64-darwin.  Fixes the failure shown in 
https://bugs.kde.org/show_bug.cgi?id=254646#c13
Keep the stack properly 16 aligned when delivering signals on x86-darwin.
Fix up debug printing -- no functional change.
Make this compile on Darwin.
rlimit64_nofile won't build on Darwin, so don't try.
Add a nasty kludge in the handling of mmap on Darwin.  Does not apply
to any other platforms.  Prevent mmap(ANON) from returning zero (zero
with success, that is) since (a) some programs are observed to be
spooked by getting zero from a successful call to mmap, and (b) it's
pretty stupid from the point of view of program safety and possibly
security, since it causes page zero to become accessible.  So don't.
/* Do expensive interpretation for Iop_Add32 and Iop_Add64 on
   Darwin.  10.7 is mostly built with LLVM, which uses these for
   bitfield inserts, and we get a lot of false errors if the cheap
   interpretation is used, alas.  Could solve this much better if
   we knew which of such adds came from x86/amd64 LEA instructions,
   since these are the only ones really needing the expensive
   interpretation, but that would require some way to tag them in
   the _toIR.c front ends, which is a lot of faffing around.  So
   for now just use the slow and blunt-instrument solution. */

Pertains to, although does not completely solve, #242137.
Update the memcpy intercept for Helgrind in accordance with that
for Memcheck.  Fixes #293855.
Add some more suppressions for OSX 10.7.2.
Fix bug 297078 gdbserver signal handling problems caused by diff vki nr/gdb nr and
    non reset of "C-ontinued" signal

* To allow vki signame to be used in debuglog:
  - pub_core_signals.h : added prototype for Char *VG_(signame)
  - m_signals.c : changed static const Char *signame(Int sigNo)
                      to const Char *VG_(signame)(Int sigNo)

* valgrind-low.c : when the signal to report to gdb has
  been reported, clear it so that it is not reported anymore
  afterwards.

* m_gdbserver.c: when checking in pass_signals if signal
  can be passed without gdb interaction, do a conversion
  from vki nr to gdb nr when indexing
  (as pass_signals[] is indexed by gdb_nr).

* various gdbserver files:
  - used vki_ prefix for some args and variables to clarify
  - better debuglog tracing

* modified nlpasssigalrm.vgtest to test SIGCHLD signal
  handling followed by a break (to see SIGTRAP is properly
  given to gdb).
Further fix 297078 : implement conversion between vki and gdb real time sig nr.

* gdbserver_tests/nlpasssigalrm
   modify test so as to test also a real time signal

* coregrind/m_gdbserver/signals.c
  - implement translation between gdb real time signal numbers
    and vki real time signal numbers
  - ensure non-convertible signals are giving an error
Fix #ifdef vs { mismatch in r12471, that broke compilation on MacOS.
gcc-4.7.0 complains about some __attribute__((always_inline)) here,
so change them back to vanilla ones.
drd: Don't complain about stack variables that are shared over threads. Closes #297147
drd: Reenable reporting races on stack variables that are shared over threads for --check-stack-var=yes.
Initial support for POWER Processor decimal floating point
instruction support -- VEX side changes.  See #295221.

This patch adds test cases.  Also adds some minor Memcheck
instrumentation tweaks necessitated by the IR changes.
Add .gitignore.
Add VEX as a submodule