- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

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

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

Update jemalloc to version 3.4.0.

Import jemalloc 3.3.0. This reduces zeroed memory validation overhead for
non-MALLOC_PRODUCTION builds.

Import jemalloc 3.2.0.

Import jemalloc 3.0.0. This fixes memory zeroing bugs that manifested as
jemalloc assertion failures for debug builds, or as calloc() sometimes
returning non-zeroed memory for production builds.

Import jemalloc 37b6f95dcd866f51c91488531a2efc3ed4c2b754 (dev branch,
prior to 3.0.0 release). This version is likely very close to what will be
3.0.0.

Work around llvm PR 12623, which makes variables declared with .symver
sometimes disappear from the resulting object file, if compiled with
clang. In particular, this can lead to errors when building world with
clang and -g, similar to:

/usr/obj/usr/src/tmp/usr/lib/libc.so: undefined reference to `_malloc_options'

Reported by: Conrad J. Sabatier <conrads@.no.cox.net>
Reviewed by: jasone

Import jemalloc a8f8d7540d66ddee7337db80c92890916e1063ca (dev branch,
prior to 3.0.0 release). This fixes several bugs related to memory
initialization.

Mangle __jemalloc_a0{malloc,calloc,free}() just like all the other
library-internal symbols in jemalloc, and adjust the tls allocation code
in libc to use the mangled names.

Import jemalloc 606f1fdc3cdbc700717133ca56685313caea24bb (dev branch,
prior to 3.0.0 release), and mangle internal symbols.

Import jemalloc 9ef7f5dc34ff02f50d401e41c8d9a4a928e7c2aa (dev branch,
prior to 3.0.0 release) as contrib/jemalloc, and integrate it into libc.
The code being imported by this commit diverged from
lib/libc/stdlib/malloc.c in March 2010, which means that a portion of
the jemalloc 1.0.0 ChangeLog entries are relevant, as are the entries
for all subsequent releases.