libstdc++: Fix build failure on AArch64 ILP32 [PR98370]

This should fix a build failure on AArch64 ILP32 due to int32_t mapping
to long int instead of int on this platform, which causes type deduction
to fail in the below call to std::max as reported in the PR.

libstdc++-v3/ChangeLog:

	PR libstdc++/98370
	* src/c++17/floating_to_chars.cc (__floating_to_chars_shortest):
	Provide explicit template arguments to the call to std::max.