gitweb cleanup: Move @diff_opts declaration earlier

Move @diff_opts declaration earlier, so that all gitweb options are
together (and not separated by %feature hash and some subroutines),
with the exception of $GITWEB_CONFIG which must be after all option
variables including %feature hash.

While at it, in the moved comment, note that diff option '-C' implies
'-M', instead of suggesting that '-M', '-C' is required.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/gitweb.perl

@@ -104,6 +104,16 @@ BEGIN
 # could be even 'utf-8' for the old behavior)
 our $fallback_encoding = 'latin1';
 
+# rename detection options for git-diff and git-diff-tree
+# - default is '-M', with the cost proportional to
+#   (number of removed files) * (number of new files).
+# - more costly is '-C' (which implies '-M'), with the cost proportional to
+#   (number of changed files + number of removed files) * (number of new files)
+# - even more costly is '-C', '--find-copies-harder' with cost
+#   (number of files in the original tree) * (number of new files)
+# - one might want to include '-B' option, e.g. '-B', '-M'
+our @diff_opts = ('-M'); # taken from git_commit
+
 # You define site-wide feature defaults here; override them with
 # $GITWEB_CONFIG as necessary.
 our %feature = (
@@ -310,16 +320,6 @@ sub check_export_ok {
 		(!$export_ok || -e "$dir/$export_ok"));
 }
 
-# rename detection options for git-diff and git-diff-tree
-# - default is '-M', with the cost proportional to
-#   (number of removed files) * (number of new files).
-# - more costly is '-C' (or '-C', '-M'), with the cost proportional to
-#   (number of changed files + number of removed files) * (number of new files)
-# - even more costly is '-C', '--find-copies-harder' with cost
-#   (number of files in the original tree) * (number of new files)
-# - one might want to include '-B' option, e.g. '-B', '-M'
-our @diff_opts = ('-M'); # taken from git_commit
-
 our $GITWEB_CONFIG = $ENV{'GITWEB_CONFIG'} || "++GITWEB_CONFIG++";
 do $GITWEB_CONFIG if -e $GITWEB_CONFIG;