C:\DEV\SDL_PERL\SDL-DEVEL-1.2.8-VC6
\---SDL-1.2.8
    +---docs
    |   \---html
    +---include
    \---lib

##</code><code>##

use File::Spec;
for my $inc ( @include_dirs ){
    if( -e File::Spec->catfile( $inc, 'SDL.h' ){
        die "Congratulation, you've got  SDL.h";
    }
}