IOstreams: Remove obsolete MSVC version check

[SVN r85900]
Remove obsolete MSVC check from pragma guard

 git grep -h -B1 "^#\s*pragma once" | grep -v pragma | sort | uniq

is now clean.

[SVN r85952]
IOStreams: Remove obsolete GCC version checks.

[SVN r86078]
IOStreams: Remove obsolete MSVC version checks.

[SVN r86079]
IOStreams: Remove use of obsolete macro.

[SVN r86080]
Remove BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

Process #ifndef...#endif conditions.

[SVN r86244]
Remove BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

Process #ifndef...#else...#endif blocks.

[SVN r86245]