Add check for madvise(2) to configure.ac.

Some platforms, such as Google's Portable Native Client, use Newlib and
thus lack access to madvise(2).  In those instances, pages_purge() is
transformed into a no-op.
Configure for Rust.
Check for __builtin_ffsl before ffsl.

When building with -O0, GCC doesn't use builtins for ffs and ffsl calls,
and uses library function calls instead. But the Android NDK doesn't have
those functions exported from any library, leading to build failure.
However, using __builtin_ffs* uses the builtin inlines.
Use JEMALLOC_INTERNAL_FFSL in STATIC_PAGE_SHIFT test
Support for iOS compilation
Ensure the default purgeable zone is after the default zone on OS X
Allow to build with clang-cl
Fix unportable == operator in configure scripts

Now this code is more portable and now people can use faster shells than
Bash such as Dash.

To use a faster shell with autoconf set the CONFIG_SHELL environment
variable to the shell and run the configure script with the shell.
Merge pull request #88 from sstewartgallus/fix-bashisms

Fix unportable == operator in configure scripts
Add OpenRISC/or1k LG_QUANTUM size definition
Update config.{guess,sub} to more recent versions, to add better support to OpenRISC/or1k (among others)
Support DragonFlyBSD

Note that in contrast to FreeBSD, DragonFly does not work
with force_lazy_lock enabled.
Merge pull request #96 from manuelafm/dev

Please add support for OpenRISC/or1k architecture
Remove ${srcroot} from cfghdrs_in, cfgoutputs_in and cfghdrs_tup in configure

On Windows, srcroot may start with "drive:", which confuses autoconf's
AC_CONFIG_* macros. The macros works equally well without ${srcroot},
provided some adjustment to Makefile.in.
Merge pull request #102 from mneumann/dfly

Support DragonFlyBSD
Fix the bug that causes not allocating free run with lowest address.
Reintroduce the comment that was removed in f9ff603.
Merge pull request #103 from wqfish/dev

Fix the bug that causes not allocating free run with lowest address.

This fixes a regression due to f9ff60346d7c25ad653ea062e496a5d0864233b2,
which was never incorporated into a release.
Add atomic operations tests and fix latent bugs.
Fix the cactive statistic.

Fix the cactive statistic to decrease (rather than increase) when active
memory decreases.  This regression was introduced by
aa5113b1fdafd1129c22512837c6c3d66c295fc8 (Refactor overly large/complex
functions) and first released in 3.5.0.