gitweb: hard-depend on the Digest::MD5 5.8 module

Since my d48b284183 ("perl: bump the required Perl version to 5.8 from
5.6.[21]", 2010-09-24), we've depended on 5.8, so there's no reason to
conditionally require Digest::MD5 anymore. It was released with perl
v5.7.3[1]

The initial introduction of the dependency in
e9fdd74e53 ("gitweb: (gr)avatar support", 2009-06-30) says as much,
this also undoes part of the later 2e9c8789b7 ("gitweb: Mention
optional Perl modules in INSTALL", 2011-02-04) since gitweb will
always be run on at least 5.8, so there's no need to mention
Digest::MD5 as a required module in the documentation, let's instead
say that we require perl 5.8.

1. $ corelist Digest::MD5
   Data for 2015-02-14
   Digest::MD5 was first released with perl v5.7.3

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/INSTALL

@@ -29,12 +29,11 @@ Requirements
 ------------
 
  - Core git tools
- - Perl
+ - Perl 5.8
  - Perl modules: CGI, Encode, Fcntl, File::Find, File::Basename.
  - web server
 
 The following optional Perl modules are required for extra features
- - Digest::MD5 - for gravatar support
  - CGI::Fast and FCGI - for running gitweb as FastCGI script
  - HTML::TagCloud - for fancy tag cloud in project list view
  - HTTP::Date or Time::ParseDate - to support If-Modified-Since for feeds

gitweb/gitweb.perl

@@ -20,6 +20,8 @@ use Fcntl ':mode';
 use File::Find qw();
 use File::Basename qw(basename);
 use Time::HiRes qw(gettimeofday tv_interval);
+use Digest::MD5 qw(md5_hex);
+
 binmode STDOUT, ':utf8';
 
 if (!defined($CGI::VERSION) || $CGI::VERSION < 4.08) {
@@ -490,7 +492,6 @@ our %feature = (
 	# Currently available providers are gravatar and picon.
 	# If an unknown provider is specified, the feature is disabled.
 
-	# Gravatar depends on Digest::MD5.
 	# Picon currently relies on the indiana.edu database.
 
 	# To enable system wide have in $GITWEB_CONFIG
@@ -1166,18 +1167,8 @@ sub configure_gitweb_features {
 	our @snapshot_fmts = gitweb_get_feature('snapshot');
 	@snapshot_fmts = filter_snapshot_fmts(@snapshot_fmts);
 
-	# check that the avatar feature is set to a known provider name,
-	# and for each provider check if the dependencies are satisfied.
-	# if the provider name is invalid or the dependencies are not met,
-	# reset $git_avatar to the empty string.
 	our ($git_avatar) = gitweb_get_feature('avatar');
-	if ($git_avatar eq 'gravatar') {
-		$git_avatar = '' unless (eval { require Digest::MD5; 1; });
-	} elsif ($git_avatar eq 'picon') {
-		# no dependencies
-	} else {
-		$git_avatar = '';
-	}
+	$git_avatar = '' unless $git_avatar =~ /^(?:gravatar|picon)$/s;
 
 	our @extra_branch_refs = gitweb_get_feature('extra-branch-refs');
 	@extra_branch_refs = filter_and_validate_refs (@extra_branch_refs);
@@ -2167,7 +2158,7 @@ sub gravatar_url {
 	my $size = shift;
 	$avatar_cache{$email} ||=
 		"//www.gravatar.com/avatar/" .
-			Digest::MD5::md5_hex($email) . "?s=";
+			md5_hex($email) . "?s=";
 	return $avatar_cache{$email} . $size;
 }