PR libstdc++/88113 use size_type consistently instead of size_t

PR libstdc++/88113 use size_type consistently instead of size_t

On 16-bit msp430-elf size_t is either 16 bits or 20 bits, and so can't
represent all values of the uint32_t type used for bitset::size_type.
Using the smaller of size_t and uint32_t for size_type ensures it fits
in size_t.

	PR libstdc++/88113
	* src/c++17/memory_resource.cc (bitset::size_type): Use the smaller
	of uint32_t and size_t.
	(bitset::size(), bitset::free(), bitset::update_next_word())
	(bitset::max_blocks_per_chunk(), bitset::max_word_index()): Use
	size_type consistently instead of size_t.
	(chunk): Adjust static_assert checking sizeof(chunk).

From-SVN: r266352