Standardize order of use strict and use warnings in Perl code

The standard order in PostgreSQL and other code is use strict first,
but some code was uselessly inconsistent about this.

doc/src/sgml/generate-errcodes-table.pl

@@ -3,8 +3,8 @@
 # Generate the errcodes-table.sgml file from errcodes.txt
 # Copyright (c) 2000-2020, PostgreSQL Global Development Group
 
-use warnings;
 use strict;
+use warnings;
 
 print
   "<!-- autogenerated from src/backend/utils/errcodes.txt, do not edit -->\n";

src/backend/parser/check_keywords.pl

@@ -6,8 +6,8 @@
 # src/backend/parser/check_keywords.pl
 # Copyright (c) 2009-2020, PostgreSQL Global Development Group
 
-use warnings;
 use strict;
+use warnings;
 
 my $gram_filename   = $ARGV[0];
 my $kwlist_filename = $ARGV[1];

src/backend/storage/lmgr/generate-lwlocknames.pl

@@ -3,8 +3,8 @@
 # Generate lwlocknames.h and lwlocknames.c from lwlocknames.txt
 # Copyright (c) 2000-2020, PostgreSQL Global Development Group
 
-use warnings;
 use strict;
+use warnings;
 
 my $lastlockidx = -1;
 my $continue    = "\n";

src/backend/utils/generate-errcodes.pl

@@ -3,8 +3,8 @@
 # Generate the errcodes.h header from errcodes.txt
 # Copyright (c) 2000-2020, PostgreSQL Global Development Group
 
-use warnings;
 use strict;
+use warnings;
 
 print
   "/* autogenerated from src/backend/utils/errcodes.txt, do not edit */\n";

src/pl/plpgsql/src/generate-plerrcodes.pl

@@ -3,8 +3,8 @@
 # Generate the plerrcodes.h header from errcodes.txt
 # Copyright (c) 2000-2020, PostgreSQL Global Development Group
 
-use warnings;
 use strict;
+use warnings;
 
 print
   "/* autogenerated from src/backend/utils/errcodes.txt, do not edit */\n";

src/pl/plpython/generate-spiexceptions.pl

@@ -3,8 +3,8 @@
 # Generate the spiexceptions.h header from errcodes.txt
 # Copyright (c) 2000-2020, PostgreSQL Global Development Group
 
-use warnings;
 use strict;
+use warnings;
 
 print
   "/* autogenerated from src/backend/utils/errcodes.txt, do not edit */\n";

src/pl/tcl/generate-pltclerrcodes.pl

@@ -3,8 +3,8 @@
 # Generate the pltclerrcodes.h header from errcodes.txt
 # Copyright (c) 2000-2020, PostgreSQL Global Development Group
 
-use warnings;
 use strict;
+use warnings;
 
 print
   "/* autogenerated from src/backend/utils/errcodes.txt, do not edit */\n";