boost: fix build for x32

Commit: d336110b94 boost: update to 1.67.0

dropped the patch that ensured boost doesn't over-ride the architecture flags
set by us resulting in errors:

| build/tmp/work/x86_64_x32-poky-linux-gnux32/boost/1.69.0-r0/recipe-sysroot/usr/include/bits/long-double.h:44:10: fatal error: bits/long-double-64.h: No such file or directory
| #include <bits/long-double-64.h>
|          ^~~~~~~~~~~~~~~~~~~~~~~
| compilation terminated.

Remove the relevant part from gcc.jam again to ensure we are passing
them correctly again.

Fixes [YOCTO #13598]

(From OE-Core rev: aad28f42)

Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit ebbfe23a)
Signed-off-by: Armin Kuster <akuster808@gmail.com>