install_prereq: Support package manager DNF and yum option strict=1.

This re-enables the script ./contrib/scripts/install_prereq on Fedora 22 and
newer, and on RHEL/CentOS when the option strict=1 was set for yum install.

ASTERISK-27598
Reported by: Hunter Stevens, Said Masoud

Change-Id: I40f9517122aaa6906e8fc0962b4b8008dfddb368