Extend checks on build prerequisites for building OpenWRT core

OpenWRT requires a number of Perl modules to be installed. It wasn't checking on all of them.
This patch adds checks for Perl FindBin, File::Copy, File::Compare and Thread::Queue modules.

Failing to install these, will have the build break at some point. By adding these to the
prereq-build.mk script, they are checked on forehand.

Tested on a Fedora 33 and 34 (beta) that was freshly installed. Fedora appears to
break up Perl modules into small packages that need to be installed for the build to succeed.

Signed-off-by: Bas Mevissen <abuse@basmevissen.nl>
(cherry picked from commit f68c9474ac)

include/prereq-build.mk

@@ -65,11 +65,22 @@ $(eval $(call TestHostCommand,perl-data-dumper, \
 	Please install the Perl Data::Dumper module, \
 	perl -MData::Dumper -e 1))
 
+$(eval $(call TestHostCommand,perl-findbin, \
+	Please install the Perl FindBin module, \
+	perl -MFindBin -e 1))
+
+$(eval $(call TestHostCommand,perl-file-copy, \
+	Please install the Perl File::Copy module, \
+	perl -MFile::Copy -e 1))
+
+$(eval $(call TestHostCommand,perl-file-compare, \
+	Please install the Perl File::Compare module, \
+	perl -MFile::Compare -e 1))
+
 $(eval $(call TestHostCommand,perl-thread-queue, \
 	Please install the Perl Thread::Queue module, \
 	perl -MThread::Queue -e 1))
 
-
 $(eval $(call SetupHostCommand,tar,Please install GNU 'tar', \
 	gtar --version 2>&1 | grep GNU, \
 	gnutar --version 2>&1 | grep GNU, \