scripts: enable strict warnings in Perl where missing, fix fallouts

- add 'use warnings' and 'use strict' where missing from Perl scripts.
- fix 'Use of uninitialized value'.
- fix missing declarations.
- test1140.pl: fix 'Possible precedence issue with control flow operator'.
- fix other misc issues.

Most actual errors found during this PR were fixed and merged via
separate PRs.

Likely there are remaining warnings not found and fixed in this PR.

Closes #17877

.github/scripts/badwords.pl

@@ -13,7 +13,15 @@
 #
 # ---(accepted word)
 #
-my $w;
+
+use strict;
+use warnings;
+
+my @whitelist;
+my %alt;
+my %exactcase;
+
+my @w;
 while(<STDIN>) {
     chomp;
     if($_ =~ /^#/) {

.github/scripts/cleancmd.pl

@@ -10,6 +10,11 @@
 # might have a problem with that we still deem is fine.
 #
 
+use strict;
+use warnings;
+
+my @asyms;
+
 open(S, "<./docs/libcurl/symbols-in-versions")
     || die "can't find symbols-in-versions";
 while(<S>) {

.github/scripts/cmp-config.pl

@@ -23,6 +23,9 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 my $autotools = $ARGV[0];
 my $cmake = $ARGV[1];
 

.github/scripts/randcurl.pl

@@ -18,6 +18,9 @@
 # directory where it runs.
 #
 
+use strict;
+use warnings;
+
 my $curl = "../src/curl";
 my $url = "localhost:7777"; # not listening to this
 
@@ -31,6 +34,14 @@ if(!$seconds) {
 }
 print "Run $curl for $seconds seconds\n";
 
+my @opt;
+my %arg;
+my %uniq;
+my %allrc;
+
+my $totalargs = 0;
+my $totalcmds = 0;
+
 my $counter = 0xabcdef + time();
 sub getnum {
     my ($max) = @_;
@@ -164,6 +175,7 @@ sub runconfig {
         my $o = getnum($nopts);
         my $option = $opt[$o];
         my $ar = "";
+        $uniq{$option} = 0 if(!exists $uniq{$option});
         $uniq{$option}++;
         if($arg{$option}) {
             $ar = " ".randarg();

.github/scripts/trimmarkdownheader.pl

@@ -7,7 +7,10 @@
 # Outputs: the same file, minus the header
 #
 
-my $f = $ARGV[0];
+use strict;
+use warnings;
+
+my $f = $ARGV[0] || '';
 
 open(F, "<$f") or die;
 

.github/scripts/verify-examples.pl

@@ -23,12 +23,15 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 my @files = @ARGV;
 my $cfile = "test.c";
 my $check = "./scripts/checksrc.pl";
-my $error;
+my $error = 0;
 
-if($files[0] eq "-h") {
+if(!@files || $files[0] eq "-h") {
     print "Usage: verify-examples [markdown pages]\n";
     exit;
 }
@@ -82,7 +85,7 @@ sub extract {
     return ($fail ? 0 : $l);
 }
 
-my $count;
+my $count = 0;
 for my $m (@files) {
     #print "Verify $m\n";
     my $out = extract($m);

.github/scripts/verify-synopsis.pl

@@ -23,10 +23,13 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 my @files = @ARGV;
 my $cfile = "test.c";
 
-if($files[0] eq "-h") {
+if(!@files || $files[0] eq "-h") {
     print "Usage: verify-synopsis [man pages]\n";
     exit;
 }