Fix wasm loader integrity checks for opcode ref.func and opcode else:
for opcode ref.func, the function must be an import, exported, or present in a
table elem segment or global initializer to be used as the operand to ref.func,
for opcode else, there must not be an else opcode previously.
Reported in #3336 and #3337.
And fix mini loader PUSH_MEM_OFFSET/POP_MEM_OFFSET macro
definitions due to the introducing of memory64 feature.
18d363029c