Conform to the Packaging Guidelines for Perl

Add BuildRequires: perl-interpreter (or perl on systems that do not
provide perl-interpreter) since perl is invoked during the build
process.

(https://fedoraproject.org/wiki/Packaging:Perl#Build_Dependencies,
https://fedoraproject.org/wiki/Changes/perl_Package_to_Install_Core_Modules)

Probably no functional change, since perl is being brought in via other
deps.

git.spec

@@ -21,9 +21,11 @@
 %if 0%{?fedora} || 0%{?rhel} > 7
 %bcond_without              python3
 %global use_perl_generators 1
+%global use_perl_interpreter 1
 %else
 %bcond_with                 python3
 %global use_perl_generators 0
+%global use_perl_interpreter 0
 %endif
 
 # Settings for Fedora and EL >= 7
@@ -150,6 +152,11 @@ BuildRequires:  perl(Test)
 %if %{use_perl_generators}
 BuildRequires:  perl-generators
 %endif
+%if %{use_perl_interpreter}
+BuildRequires:  perl-interpreter
+%else
+BuildRequires:  perl
+%endif
 %if %{bashcomp_pkgconfig}
 BuildRequires:  pkgconfig(bash-completion)
 %endif
@@ -895,6 +902,9 @@ make test || ./print-failed-test-output
 %{?with_docs:%{_pkgdocdir}/git-svn.html}
 
 %changelog
+* Fri Apr 13 2018 Pavel Cahyna <pcahyna@redhat.com>
+- Use BuildRequires: perl-interpreter per the packaging guidelines
+
 * Tue Apr 10 2018 Todd Zullinger <tmz@pobox.com> - 2.17.0-2
 - Require perl-generators on EL > 7