...originally introduced with bd60d411 "Handle
oveflow in O(U)String::toInt() functions."  As pointed out by Noel Power, there
is existing code using toInt32(16) to read an effectively unsigned hex string
into a sal_Int32, which used to work fine with the wrap-around overflow but now
fails when toInt32 explicitly returns 0 for large values.  See, e.g., use of
oox::AttributeList::getIntegerHex (indirectly calling OUString::toInt32) in
ColorScaleRule::importColor (sc/source/filter/oox/condformatbuffer.cxx).

To prevent any regressions in LO 4.1, remove the explicit checks from
toInt{32,64} again for now.  (They were "merely" added as a general safety
measure, not to address some specific problem, IIRC.)  On master, the approach
will rather be to introduce toUInt32 and adapt client code as necessary.

Change-Id: Id332cff18a99b8bd2dcccd7988b7aad3a9e98c4c