Add ranges_size_t and rename all_view (LWG 3335)
Remove converting constructors from views (LWG 3280)
uninitialized_construct_using_allocator should use construct_at (LWG 3321)
Add nodiscard to polymorphic_allocator members (LWG 3304)
"safe" in several library names is misleading (LWG 3379)
tuple_element_t is also wrong for const subrange (LWG 3398)

Tested powerpc64le-linux, committed to master.