Work around to get llvm-mingw working on aarch64

Work around to get llvm-mingw working on aarch64

It looks like llvm-mingw tool chain does not understand `.previous` asm
directive (see https://sourceware.org/binutils/docs/as/Previous.html).
As a workaround for win64 flavor (llvm-mingw toolchain) we let xlate
to emit .text instead of emitting .previous.

We also need to revisit usage of win64 flavor here in aarch64. We should
perhaps introduce a mingw flavour on aarch64 as well. win assembly
flavour should be used for microsoft assembler.

Fixes #26415

Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/26428)