Patch to improve style of generate_history.pl perl script

I have applied the attached patch to improve the style of our
generate_history.pl perl script.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +
diff --git a/doc/src/sgml/generate_history.pl b/doc/src/sgml/generate_history.pl
new file mode 100644
index 2b81569..a6c0bd7
*** a/doc/src/sgml/generate_history.pl
--- b/doc/src/sgml/generate_history.pl
***************
*** 13,22 ****

  use strict;

! my($srcdir) = shift;
! defined($srcdir) || die "$0: missing required argument: srcdir\n";
! my($infile) = shift;
! defined($infile) || die "$0: missing required argument: inputfile\n";

  # Emit DOCTYPE header so that the output is a self-contained SGML document
  print "<!DOCTYPE appendix PUBLIC \"-//OASIS//DTD DocBook V4.2//EN\">\n";
--- 13,22 ----

  use strict;

! my $srcdir = shift;
! die "$0: missing required argument: srcdir\n" if !defined($srcdir);
! my $infile = shift;
! die "$0: missing required argument: inputfile\n" if !defined($infile);

  # Emit DOCTYPE header so that the output is a self-contained SGML document
  print "<!DOCTYPE appendix PUBLIC \"-//OASIS//DTD DocBook V4.2//EN\">\n";
*************** process_file($infile);
*** 26,36 ****
  exit 0;

  sub process_file {
!     my($filename) = @_;

      local *FILE;        # need a local filehandle so we can recurse

!     my($f) = $srcdir . '/' . $filename;
      open(FILE, $f) || die "could not read $f: $!\n";

      while (<FILE>) {
--- 26,36 ----
  exit 0;

  sub process_file {
!     my $filename = shift;

      local *FILE;        # need a local filehandle so we can recurse

!     my $f = $srcdir . '/' . $filename;
      open(FILE, $f) || die "could not read $f: $!\n";

      while (<FILE>) {