Configurations: PowerPC is big endian
Configurations: PowerPC is big endian

Define B_ENDIAN on PowerPC because it is a big endian architecture. With
this change the BN* related tests pass.

Fixes: #12199

Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>

Reviewed-by: Richard Levitte <5fb523282dd7956571c80524edc2dccfa0bd8234@openssl.org>
Reviewed-by: Paul Dale <bc4a6b4cd7a8395c734c8eb5aef04a9c30188c85@oracle.com>
Reviewed-by: Tomas Mraz <973cc78d8b4cb00714230ba9be0225e917ab4ac6@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/12371)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl