Random: Remove obsolete MSVC version check.

[SVN r86030]
Remove BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

Process #ifndef...#endif conditions.

[SVN r86244]
Remove BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

Process #ifdef...#else...#endif blocks.

[SVN r86246]
random: avoid generating warnings with -Wshadow, fix #9115

[SVN r86321]
random: add explicit casts in normal_distribution.hpp to avoid truncation warnings with MSVC

[SVN r86325]