Fix out of bounds vector write in Logger::addOutput(ILogOutput *out)

Fix out of bounds vector write in Logger::addOutput(ILogOutput *out)

Previously, the invocation of Logger::addOutput(ILogOutput *out) led to
an out of bounds write of the m_outputs vector, resulting in the
m_silenced_levels array being modified.

Fortunately, the only caller of that method was android system logging,
and only since a few commits ago.