avoid localtime() exception if param is undef

if localtime() parameter is undef, it will generate an exception.
To avoid that, we check first if $time is true.

Jairo and Mario, you deserve a big thanks for this bug.

closes: #1813

Reported-by: Mario Jorge De Sousa Freire <mario.freire@camara.gov.br>
Reported-by: Jairo C de Oliveira <olivejai@gmail.com>

lib/FusionInventory/Agent/Tools.pm

@@ -57,6 +57,8 @@ if ($OSNAME ne 'MSWin32') {
 sub getFormatedLocalTime {
     my ($time) = @_;
 
+    return unless $time;
+
     my ($year, $month , $day, $hour, $min, $sec) =
         (localtime ($time))[5, 4, 3, 2, 1, 0];