Incorrect length & capacity calculation in ByteBuffer::destroy_into_vec_struct

[Grimeh]

ByteBuffer::destroy_into_vec_struct multiplies the length & capacity of the byte buffer by the size of the struct, however it should divide by the size to go from number of bytes to number of elements.

csbindgen/csbindgen-tests/src/lib.rs

Lines 590 to 591 in 768761c

	let length = (self.length * element_size) as usize;
	let capacity = (self.capacity * element_size) as usize;

csbindgen/README.md

Lines 956 to 957 in 768761c

	let length = (self.length * element_size) as usize;
	let capacity = (self.capacity * element_size) as usize;