[boost] [android] New compilers: gcc-5.2 and clang-3.7

Hi all, We've added new compilers into CrystaX NDK recently: gcc-5.2 and clang-3.7 (old gcc-4.9 and clang-3.6 still there too). Testing results should appear on Boost regression page in a few days. Both compilers have fully passed our automatic tests, but you know, there still could be bugs, especially in such complicate projects. We're asking all maintainers of the Boost libraries look on that results and report us bugs (if any) to https://tracker.crystax.net/projects/ndk. The most important for us is catching regressions caused by new compilers compared to theirs previous versions. In case of such bugs, please don't add workarounds into Boost code; better report and let us fix them in CrystaX NDK. Thank you. -- Dmitry Moskalchuk