integer_log2.hpp and lowest_bit.hpp, in boost/pending/: little comment cleanup (svn anchors, etc.); added a static_cast<> to silence (harmless) MSVC++ warnings

[SVN r48251]

libs/detail

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-Subproject commit 06946f66073853f8a99650b6a88cbee741b43819
+Subproject commit 18dbae470094879cadc732688b8408e028b074c0

libs/dynamic_bitset

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-Subproject commit a8998ae8a0199244781701c277f3eebc1bb21687
+Subproject commit eef25927d70889f51e149adf10d359789240a5a1