rapidjson

Guard against min/max being macros in reader.h

Sometimes, particularly when Microsoft's windows.h is included, min/max
are defined as macros, interfering with use of
std::numeric_limits::min() and the like.

To guard against this, the function name is wrapped in an extra set of
parenthesis, which inhibits function-style macro expansion.

This is a similar commit to 6e38649ec6, but fixes uses of
std::numeric_limits added after that commit, like those introduced in
2ea43433e2.