perl5db.pl: Fix regex in cmd_a allowing short actions

The regex pattern in the `a` command was updated from `(\S.+)` to
`(\S.*)` to correctly handle short actions, including single-character
expressions after the line number.

Signed-off-by: Sergei Zhmylev <zhmylove@narod.ru>

.mailmap

@@ -785,6 +785,7 @@ Scott Wiersdorf <scott@perlcode.org> scott@perlcode.org <scott@perlcode.org>
 Sean Davis <dive@endersgame.net> Sean Davis <dive@ender.com>
 Sebastian Schmidt <yath@yath.de> <yath@yath.de>
 Sebastian Schmidt <yath@yath.de> yath-perlbug@yath.de <yath-perlbug@yath.de>
+Sergey Zhmylove <zhmylove@narod.ru> Sergei Zhmylev <zhmylove@narod.ru>
 Sergey Zhmylove <zhmylove@narod.ru> zhmylove <zhmylove@narod.ru>
 Shawn M Moore <sartak@gmail.com> Shawn M Moore <code@sartak.org>
 Shawn M Moore <sartak@gmail.com> Shawn M Moore <sartak@bestpractical.com>

lib/perl5db.pl

@@ -4798,7 +4798,7 @@ sub cmd_a {
     $line =~ s/\A\./$dbline/;
 
     # Should be a line number followed by an expression.
-    if ( my ($lineno, $expr) = $line =~ /^\s*(\d*)\s*(\S.+)/ ) {
+    if ( my ($lineno, $expr) = $line =~ /^\s*(\d*)\s*(\S.*)/ ) {
 
         if (! length($lineno)) {
             $lineno = $dbline;
@@ -4826,7 +4826,7 @@ sub cmd_a {
                 _set_breakpoint_enabled_status($filename, $lineno, 1);
             }
         } ## end if (length $expr)
-    } ## end if ($line =~ /^\s*(\d*)\s*(\S.+)/)
+    } ## end if ($line =~ /^\s*(\d*)\s*(\S.*)/)
     else {
 
         # Syntax wrong.