[boost] Patch for smart_ptr with Sun CC 5.3 to avoid compiler internal error

From: Baptiste Lepilleur (blepctc_at_[hidden])
Date: 2003-05-16 02:18:50

    Sun CC 5.3 as a problem with the safe bool idiom, which result in a
compiler internal error when bool conversion is used.

    The attached patch (based on boost 1.30) implements the work-around used
by Boost.Function library for Sun CC 5.3 (implement a simple bool conversion
operator).

    There is probably other libraries in boost that could use that
work-around.

    Baptiste.