[boost] [shared_ptr] Workaround for vc7.1 bug

From: David Abrahams (dave_at_[hidden])
Date: 2006-02-18 13:38:00

This failure:
http://engineering.meta-comm.com/boost-regression/CVS-HEAD/developer/output/RudbekAssociates-bin-boost-libs-graph-test-graphviz_test-test-vc-7_1-debug-threading-multi.html

Appears to be due to vc7.1 badly misinterpreting a using-directive in
the scope of the instantiating function.  I suggest full qualification
of ::boost::detail in shared_ptr.hpp as a remedy.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com