BUG/MAJOR: mux-h1: Deal with true 64-bits integer to emit chunks size

BUG/MAJOR: mux-h1: Deal with true 64-bits integer to emit chunks size

Functions emitting chunks size are using size_t integer to do so. Depending
on the code path, these functions can be called using an unsigned long long
integer (h1m->curr_len for instance). On 64-bits architectures, there is no
issue. But on the 32-bits architecture, it is a problem. size_t are 32-bits
integer so the 64-bits parameter will be casted to a 32-bits integer. For
chunk size exceeding 4GB, the wrong size will be emitted.

To fix the issue, these functions are now using true 64-bits
integer. h1s_consume_kop() was also modified accordingly.

In addition, when a size_t is compared to a 64-bits integer, an explicit
cast is used to be sure the right type is used.

This patch must be backported as far as 3.0. It must be backported after
1ef74fc7c ("BUG/MEDIUM: mux_h1: fix stack buffer overflow in
h1_append_chunk_size()").