Yes, you can use #ifdef in Perl, in combination with
the -P switch (see man perlrun). But I've never seen a serious
program using it, and I can't imagine a situation where you
want to use it.
If you want to use a module Win32::Foo only if the OS is
Windows, do something like:
use if $^O =~ /Win32/, Win32::Foo => qw /arg1 arg2 arg3/;