The Perl script build-perl-modules.pl reads:

# Don't need Class::C3::XS if you're running 5.10
if ( $] > 5.009_004 ) {
        delete $packages{'Class::C3::XS'};
}

However http://svn.slimdevices.com/repos/slim/vendor/src/7.3/ only contains:

# AutoXS-Header-0.03.tar.gz
# Class-XSAccessor-Array-0.05.tar.gz
# Compress-Zlib-1.41.tar.gz
# Cookie-XS-0.10.tar.gz
# DBD-mysql-3.0002.tar.gz
# DBI-1.604.tar.gz
# Digest-SHA1-2.11.tar.gz
# Encode-Detect-1.00.tar.gz
# GD-2.35.tar.gz
# HTML-Parser-3.48.tar.gz
# JSON-XS-1.5.tar.gz
# Locale-Hebrew-1.04.tar.gz
# Makefile.PL
# POE-XS-Queue-Array-0.002.tar.gz
# Template-Toolkit-2.15.tar.gz
# Time-HiRes-1.86.tar.gz
# XML-Parser-2.34.tar.gz
# YAML-Syck-0.64.tar.gz
# fontconfig-2.6.0.tar.gz
# freetype-2.3.7.tar.gz
# gd-2.0.35.tar.gz
# jpegsrc.v6b.tar.gz
# libpng-1.2.32.tar.gz


The http://svn.slimdevices.com/repos/slim/vendor/src/7.2/ repository contains:

# Class-C3-XS-0.08.tar.gz
# Class-XSAccessor-Array-0.05.tar.gz
# Compress-Zlib-1.41.tar.gz
# DBD-mysql-3.0002.tar.gz
# DBI-1.604.tar.gz
# Digest-SHA1-2.11.tar.gz
# Encode-Detect-1.00.tar.gz
# GD-2.35.tar.gz
# HTML-Parser-3.48.tar.gz
# JSON-XS-1.5.tar.gz
# Locale-Hebrew-1.04.tar.gz
# POE-XS-Queue-Array-0.002.tar.gz
# Template-Toolkit-2.15.tar.gz
# Time-HiRes-1.86.tar.gz
# XML-Parser-2.34.tar.gz
# YAML-Syck-0.64.tar.gz