buildroot

php: fix build for AArch64

Add a patch from a PHP Github pull request that fixes the build at -O0
on AArch64.

Signed-off-by: Tatsuyuki Ishi <ishitatsuyuki@gmail.com>
[Thomas: improved patch commit log.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>