Fix AFALG kernel and headers mismatch problem

During Configure we attempt to check the kernel version of this platform
to see whether we can compile the AFALG engine. If the kernel version
looks recent enough then we enable AFALG. However when we compile
e_afalg.c we check the version of the linux headers. If there is a
mismatch between the linux headers and the currently running kernel then
we don't compile the AFLAG engine and continue. This was causing a link
error.

Reviewed-by: Richard Levitte <levitte@openssl.org>