A fix and a test case for Bug#1051006
"Tree iterators return garbage if an index is modified between calls"

Mark in a deleted node in sptree.h that it's been  put into the
garbage heap. When iterting over a garbage collected node, skip it,
and go up the stack until we find the first valid node.

This breaks the "sorted" quality of tree iterators in case there
are modifications between invocations of an iterator:
it is possible that a node is deleted and recycled, and we don't see
it in the iterator. When we go up the stack, we can jump to a different
part of the range than the one the recycled node belongs to.
. With this fix, it is also possible, that the iteration goes more
than once over entire tree range. But it's a good enough quick fix for a
crashing expire loop, which uses the tree iterator over the primary key to
scan the entire range and deletes expired keys on the go (additionally,
deletions may occur between invocations of the expire loop).

Fix a regression with nested @finally not being
called, introduced in 1.4.7 release.

Big thanks to David Chisnall for a swift fix in GNUStep Objective C
runtime.

Add unit tests for two Objective C runtime properties:
nested finally handling and ability to catch C++ exceptions.

Do not use bundled libobjc on Darwin.
Refactor cmake scritps: introduce os.cmake, arch.cmake,
compiler.cmake, libobjc.cmake, luajit.cmake.

Remove the hack with building libobjc/luajit as a
dependency on cfg.

Do not specify -ggdb when compiling with clang.

Add -fno-objc-legacy-dispatch and -fobjc-nonfragile-abi
when compiling with CLang on Linux.

Remove -fgnu-runtime when compiling with gcc on Mac.

Many minor cleanups.

Add a makefile to libobjc.

See README in this patch for a description of the import
procedure.

Darwin revealed a bug in our free_proc_title() function, which was
added to procitle.c to work well with valgrind: we free argv pointer
even if it wasn't allocated (none of PS_USE_CLOBBER_ARGV/PS_USE_CHANGE_ARGV
was set).

Don't free memory if it wasn't allocated.

Another issue is understanding why Darwin doesn't define
PS_USE_SETPROCTITLE and why our FreeBSD port didn't hit this bug.

Extend queue.h with STAILQ_SPLICE and STAILQ_REVERSE.
Test the new functions in a simple unit testing framework.

Convert box.lua to box.lua.c and compile it in.
Fix broken out-of-source build of luajit, by adding
a few more generated files to touch-nocreate rule.

This version of libev optimizes async events significantly.

Warnings was removed. Minor coding-style cleanup.

This reverts commit 8dc70aac.

This patch introduces wal_mode configuration variable,
which can take either "fsync" or "fsync_delay" values.

In "fsync" mode, we open the write ahead log in O_SYNC
mode, and thus sync every write to disk.

Th fsync_delay mode is the backward-compatible mode:
in this mode, we only do fsync once every fsync_delay
seconds. If fsync_delay is 0, there is no fsync.

Otherwise, this patch is only adding auxiliary headers,
object files, etc.