Fix _STLP_USE_EXCEPTIONS

When _STLP_USE_EXCEPTIONS is not defined, omit all declarations
and uses of __Named_exception.  Compile and use __Named_exception
only when STLport is being allowed to use exceptions, but not the
host compiler's native version.

Change-Id: I71963ca15d535d3ae1717c5bb22fe5fa3add41cb
5 files changed