README: Clarify --with-iconv configure script option documentation.
README: Clarify --with-iconv configure script option documentation.

ccpaging/log4cplus,csuideal/log4cplus,hunter-packages/log4cplus,ccpaging/log4cplus,csuideal/log4cplus,hunter-packages/log4cplus,hunter-packages/log4cplus,hunter-packages/log4cplus,ccpaging/log4cplus,csuideal/log4cplus,ccpaging/log4cplus,csuideal/log4cplus