Use a variable instead of plain name

Author: Altai-man

xt/examples-compilation.t

@@ -5,7 +5,7 @@ use File::Find;
 
 # Extract examples
 chdir $?FILE.IO.dirname.IO.dirname;
-my $p1 = shell 'perl6 util/extract-examples.p6 --source-path=./doc/ --prefix=./examples/';
+my $p1 = shell "$*EXECUTABLE-NAME util/extract-examples.p6 --source-path=./doc/ --prefix=./examples/";
 chdir 'examples';
 
 my @files = find(dir => '.',