I'm looking these lines today (no Japanese input now).

 373 sub check_prereqs_libs {
 374   my @libs = @_;
 375   my $ret  = 1;
 376       
 377   foreach my $lib (@libs) {
 378     print "checking for $lib... ";
 379     my $found_dll          = '';
 380     my $found_lib          = '';
 381     my $found_inc          = '';
 382     my $header_map         = {
 383       'z'       => 'zlib',
 384       'jpeg'    => 'jpeglib',
 385       'vorbis'  => 'vorbisenc',
 386       'SDL_gfx' => 'SDL_gfxPrimitives',
 387       'SDL'     => 'SDL_version',
 388     };
 389     my $header             = (defined $header_map->{$lib}) ? $header_map->{$lib} : $lib;
 390 
 391     my $dlext = get_dlext();
 392     foreach (keys %$inc_lib_candidates) {
 393       my $ld = $inc_lib_candidates->{$_};
 394       next unless -d $_ && -d $ld;
 395       ($found_dll) = find_file($ld, qr/[\/\\]lib\Q$lib\E[\-\d\.]*\.($dlext[\d\.]*|so|dll)$/);
 396       $found_dll   = $1 if $found_dll && $found_dll =~/^(.+($dlext|so|dll))/ && -e $1;
 397       ($found_lib) = find_file($ld, qr/[\/\\]lib\Q$lib\E[\-\d\.]*\.($dlext[\d\.]*|a|dll.a)$/);
 398       ($found_inc) = find_file($_,  qr/[\/\\]\Q$header\E[\-\d\.]*\.h$/);
 399       last if $found_lib && $found_inc;
 400     }