Wasm loader enhancement: check code size in code entry

[TianlongLiang]

Add wasm loader check: in code entry, the code size should match the size of vec(locals) + expr, and expr should end with opcode end

[TianlongLiang]

So how about I modify the loader logic as follows:

1. check code size > len(vec(locals)) + 1 and check the END opcode at the end of the function body in load_function_section to early stop some mutated wasm file loader checking
2. in wasm_loader_prepare_bytecode, at the end only check for unbalanced control flow structures now, since it won't be unmatched code size or missing end opcodes.

[wenyongh]

LGTM

[lum1n0us]

LGTM