Update build scripts for Perl update.

This is copied from psychonic's SourceMod fixes.

Author: dvander

support/buildbot/bootstrap.pl

@@ -9,6 +9,8 @@
 my ($myself, $path) = fileparse($0);
 chdir($path);
 
+use FindBin;
+use lib $FindBin::Bin;
 require 'helpers.pm';
 
 #Go back above build dir

support/buildbot/package.pl

@@ -29,6 +29,8 @@
 my ($myself, $path) = fileparse($0);
 chdir($path);
 
+use FindBin;
+use lib $FindBin::Bin;
 require 'helpers.pm';
 
 my ($version);
@@ -155,4 +157,4 @@
 
 print "Files sent to drop site -- build succeeded.\n";
 
-exit(0);
+exit(0);

support/buildbot/startbuild.pl

@@ -5,6 +5,8 @@
 my ($myself, $path) = fileparse($0);
 chdir($path);
 
+use FindBin;
+use lib $FindBin::Bin;
 require 'helpers.pm';
 
 chdir('../../../OUTPUT');