Fixed MSVC static analyser warning.

Added multi-ABI FAQ answer.

Fixed compiler support grid being missing.

Verified works with Boost 1.58

v1.30 release

Disable valgrind headers for MSVC x64

Get tsan to print suppressions

Fixed lack of distinguish on complete_async_op().

It seems __MINGW64_VERSION_MAJOR isn't predefined.

Updated closure dispatch benchmarks with Linux results.

* Issue b11/88a (POSIX compat backend should never exceed IOV_MAX pre…

…adv() and pwritev() ops per batch.) fixed.