Add BR: perl.

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

No rebuild is required.

Build error was:

+ perl -pi.orig -e 's|confuse.h|../src/confuse.h|g' tests/check_confuse.c
/var/tmp/rpm-tmp.ojrp8F: line 39: perl: command not found

libconfuse.spec

@@ -10,6 +10,7 @@ Source0:	https://github.com/martinh/libconfuse/releases/download/v%{version}/con
 BuildRoot:      %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 
 BuildRequires:  check-devel, pkgconfig
+BuildRequires:  perl
 
 %description
 libConfuse is a configuration file parser library, licensed under