[concept_check] "Shadowed variable warning" (refs #6738)

svn path=/trunk/boost/concept_check.hpp; revision=78501
Detail: Merge some whitespace fixes from release.

svn path=/trunk/boost/concept_check.hpp; revision=80349
Concept: fix minor warning.

svn path=/trunk/boost/concept_check.hpp; revision=83983
Added unused attribute for new versions of GCC

svn path=/trunk/boost/concept/; revision=84470