Fix stack alignment issue on ia32 (#1934)

The stack of Unix-like (GCC) system should be aligned on 16-byte boundary
according to the x86-32 ABI specification.

Author: eloparco

core/iwasm/common/arch/invokeNative_ia32.s

@@ -16,9 +16,14 @@ _invokeNative:
     push    %ebp
     movl    %esp, %ebp
     movl    16(%ebp), %ecx          /* ecx = argc */
-    movl    12(%ebp), %edx          /* edx = argv */
+    leal    2(%ecx), %edx           /* edx = ecx + 2 (count return address and saved ebp) */
+    andl    $3, %edx                /* edx = edx % 4 */
+    jz   stack_aligned              /* if edx == 0, stack is already 16 bytes aligned */
+    leal    -16(%esp, %edx, 4), %esp /* esp = esp - 16 + edx * 4 */
+stack_aligned:
     test    %ecx, %ecx
     jz      skip_push_args          /* if ecx == 0, skip pushing arguments */
+    movl    12(%ebp), %edx          /* edx = argv */
     leal    -4(%edx,%ecx,4), %edx   /* edx = edx + ecx * 4 - 4 */
     subl    %esp, %edx              /* edx = edx - esp */
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