random: Initialize variable as requested by valgrind

random/jitterentropy-base.c: Init.

The variable ec does not need initialization for proper functioning of
the analyzer code. However, valgrind complains about the uninitialized
variable. Thus, initialize it.

Original-repo: https://github.com/smuellerDD/jitterentropy-library.git
Original-commit: 9048af7f06fc1488904f54852e0a2f8da45a4745
Original-Author:: Stephan Mueller <smueller@chronox.de>
Original-Date: Sun, 15 Jul 2018 19:14:02 +0200
(cherry picked from commit aa686dfc9b563ff79c01d2f8560b88f69c42ecba)

• Reported-by: Steve Grubb <sgrubb@redhat.com>
• Signed-off-by: Werner Koch <wk@gnupg.org>
• GnuPG-bug-id: T4250