lang/gcc* and MULTILIB: arm64 (aarch64) is never set up, even for main

From: Mark Millard <marklmi_at_yahoo.com>
Date: Thu, 08 Feb 2024 06:12:25 UTC
The lang/gcc*/Makefile codes like:

.if exists(/usr/lib32/libc.so)
OPTIONS_DEFINE_amd64+=          MULTILIB
OPTIONS_DEFAULT_amd64+= MULTILIB
OPTIONS_DEFINE_powerpc64+=      MULTILIB
#OPTIONS_DEFAULT_powerpc64+=    MULTILIB # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105010
MULTILIB_DESC=          Build support for 32-bit and 64-bit targets
MULTILIB_CONFIGURE_ENABLE=      multilib
.else
CONFIGURE_ARGS+=        --disable-multilib
.endif

never adds MULTILIB for aarch64 (arm64).

But these days arm64 (aarch64) has lib32 support:
14.0-RELEASE has it and main [so: 15] has it.

Is this lack of MULTILIB building deliberate for
some reason?

===
Mark Millard
marklmi at yahoo.com