Make all Perl warnings fatal

There are a lot of Perl scripts in the tree, mostly code generation
and TAP tests.  Occasionally, these scripts produce warnings.  These
are probably always mistakes on the developer side (true positives).
Typical examples are warnings from genbki.pl or related when you make
a mess in the catalog files during development, or warnings from tests
when they massage a config file that looks different on different
hosts, or mistakes during merges (e.g., duplicate subroutine
definitions), or just mistakes that weren't noticed because there is a
lot of output in a verbose build.

This changes all warnings into fatal errors, by replacing

    use warnings;

by

    use warnings FATAL => 'all';

in all Perl files.

Discussion: https://www.postgresql.org/message-id/flat/06f899fd-1826-05ab-42d6-adeb1fd5e200%40eisentraut.org

src/backend/utils/mb/Unicode/UCS_to_BIG5.pl

@@ -25,7 +25,7 @@
 #		 # and Unicode name (not used in this script)
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_EUC_CN.pl

@@ -14,7 +14,7 @@
 # and the "b" field is the hex byte sequence for GB18030
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_EUC_JIS_2004.pl

@@ -8,7 +8,7 @@
 # "euc-jis-2004-std.txt" (http://x0213.org)
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_EUC_JP.pl

@@ -12,7 +12,7 @@
 # organization's ftp site.
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_EUC_KR.pl

@@ -17,7 +17,7 @@
 #		 # and Unicode name (not used in this script)
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_EUC_TW.pl

@@ -18,7 +18,7 @@
 #		 # and Unicode name (not used in this script)
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_GB18030.pl

@@ -14,7 +14,7 @@
 # and the "b" field is the hex byte sequence for GB18030
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_JOHAB.pl

@@ -16,7 +16,7 @@
 #		 # and Unicode name (not used in this script)
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_SHIFT_JIS_2004.pl

@@ -8,7 +8,7 @@
 # "sjis-0213-2004-std.txt" (http://x0213.org)
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_SJIS.pl

@@ -11,7 +11,7 @@
 # ftp site.
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_UHC.pl

@@ -14,7 +14,7 @@
 # and the "b" field is the hex byte sequence for UHC
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/UCS_to_most.pl

@@ -16,7 +16,7 @@
 #		 # and Unicode name (not used in this script)
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use convutils;
 

src/backend/utils/mb/Unicode/convutils.pm

@@ -6,7 +6,7 @@
 package convutils;
 
 use strict;
-use warnings;
+use warnings FATAL => 'all';
 
 use Carp;
 use Exporter 'import';