LU-16353 config: enable_foo variables mustn't contains space

LU-16353 config: enable_foo variables mustn't contains space

$enable_crypto is in some circumstances set to "embedded llcrypt"
which contains a space.
When the code from lustre-build.m4 then tests the value with:

   if test x$enablecrypto = xyes

we get a syntax error from ./configure

We could add quotes to this comment, but for consistency we would need
to add quotes to ever other test for an enable_foo variable.

It is simpler just to ensure we don't add spaces.  So change the space
to a hyphen.

Lustre-change: https://review.whamcloud.com/49282
Lustre-commit: c8a33e5322b0675680f8d737f04259799d30aa0e

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I097e857409d6ec48a765ccda1cc470d28b90e601
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/49295
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>