Add BR perl.

See:
https://fedoraproject.org/wiki/Packaging:Perl#Build_Dependencies

No rebuild is required.

The original error was:

...
checking time.h presence... yes
checking for time.h... yes
checking for SSL... found in /usr
checking for HMAC_CTX_init in -lcrypto... yes
checking for EVP_sha1... yes
checking for EVP_sha256... yes
checking for dlopen... no
checking for dlopen in -ldl... yes
checking for perl... no
configure: error: perl not found

opendnssec.spec

@@ -22,6 +22,7 @@ BuildRequires: ldns-devel >= 1.6.12, sqlite-devel , openssl-devel
 BuildRequires: libxml2-devel CUnit-devel, doxygen
 # It tests for pkill/killall and would use /bin/false if not found
 BuildRequires: procps-ng
+BuildRequires: perl
 
 BuildRequires: systemd-units
 Requires(pre): shadow-utils