config: Drop linux-alpha-gcc+bwx

config: Drop linux-alpha-gcc+bwx

Its entry in Configuration/10-main.conf was dropped in commit
7ead0c89185c ("Configure: fold related configurations more aggressively
and clean-up.") probably because all but one of its bn_ops were removed
(RC4_CHAR remained). Benchmarks on an Alpha EV7 indicate that RC4_INT is
better than RC4_CHAR so rather than restoring the configuation, remove
it from config.

CLA: trivial
Bug: https://bugs.gentoo.org/697840

(cherry picked from commit 19ded1a717b6c72c3db241f06787a353f1190755)
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11130)