e_afalg: Don't warn about kernel version when pedantic

When built with --strict-warnings and the Linux kernel headers don't
match the kernel version, the preprocessor warnings in
engines/afalg/e_afalg.c cause compilation errors.  Use the macro
PEDANTIC to avoid those warnings in that case.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2095)
(cherry picked from commit 97043e46)