aot compiler: Fix the length type passed to aot_memmove/aot_memset (#3378)

The current length type of aot_memmove/aot_memset is size_t, and on
a 64 bit host it is uint64, while what the aot code passes to it is uint32,
this might lead to unexpected behavior.

ps. https://github.com/bytecodealliance/wasm-micro-runtime/pull/3376.

core/iwasm/compilation/aot_llvm.h

@@ -262,6 +262,7 @@ typedef struct AOTLLVMTypes {
     LLVMTypeRef int32_type;
     LLVMTypeRef int64_type;
     LLVMTypeRef intptr_t_type;
+    LLVMTypeRef size_t_type;
     LLVMTypeRef float32_type;
     LLVMTypeRef float64_type;
     LLVMTypeRef void_type;