php: fix a building failure on aarch64

When -O0 of gcc is used to compile the macro ZEND_SIGNED_MULTIPLY_LONG
in Zend/zend_multiply.h, the compiling will fail with the below error:
  : Assembler messages:
  :3113: Error: operand 2 should be an integer register -- `mul x1,[x29,200],[x29,192]'
  :3114: Error: operand 2 should be an integer register -- `smulh x0,[x29,200],[x29,192]'

Signed-off-by: Roy Li <rongqing.li@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>