Configure: Remove extensive debug output by default

Configure: Remove extensive debug output by default

These debug logs were added in 6e0fd246e7a (#24687), probably for
debugging the script, but they remained active by default.

Change them to appear only if OPENSSL_MKINSTALLVARS_DEBUG env var
is set.

References: 6e0fd246e7a6 "Give util/mkinstallvars.pl more fine grained control over var dependencies"

Reviewed-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
MergeDate: Tue Mar 31 00:03:14 2026
(Merged from https://github.com/openssl/openssl/pull/29083)