Fix jent_read_entropy for JENT_CPU_JITTERENTROPY_SECURE_MEMORY.

* random/jitterentropy-base.c (jent_read_entropy): Fix conditional
compile.

The call of jent_random_data had been enabled wrongly, until this
update. But it was safer side for the RNG. Peformance was bad,
though.

• GnuPG-bug-id: T5523
• Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>