Rename x86-32 assembly files from .s to .S.

Rename x86-32 assembly files from .s to .S.

Rename x86-32 assembly files from .s to .S. While processing the .S file
gcc will use the pre-processor whic will evaluate macros and ifdef. This
is turn will be used to enable the endbr32 opcode based on the __CET__
define.

Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18353)