Fix initialization of power series so that we don't get a spurious overflow error from tgamma when the result is actually zero.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@86415 b8fc166d-592f-0410-95f2-cb63ce0dd405
Merged revision(s) 85994 from trunk: Add BOOST_USE_INTRIN_H support; remove #pragma intrinsic, not needed and not supported on Intel. Refs #6646. Refs #7318. Refs #9174.


git-svn-id: http://svn.boost.org/svn/boost/branches/release@86416 b8fc166d-592f-0410-95f2-cb63ce0dd405
Merged revision(s) 85995 from trunk: Remove #pragma intrinsic( _mm_pause ); not needed, not supported on Intel. Closes #6646, #7318.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@86417 b8fc166d-592f-0410-95f2-cb63ce0dd405