Bugfix: buggy users don't read INSTALL

Probably some of them don't have the necessary prereqs to compile
either, but at least now it tells them to read the INSTALL file instead
of throwing an error about not finding 'hairtunes'.

shairport.pl

@@ -56,6 +56,14 @@ my $daemon;
 # suppose hairtunes is under same directory
 my $hairtunes_cli = $FindBin::Bin . '/hairtunes';
 
+unless (-x $hairtunes_cli) {
+    say "Can't find the 'hairtunes' decoder binary, you need to build this before using Shairport.";
+    say "Trying to build it for you anyway...";
+    system("cd ${FindBin::Bin}; make || gmake");
+    die("Nope, didn't work out. Read the INSTALL instructions!") unless -x $hairtunes_cli;
+    say "Phew! Worked out okay, by the looks of it.";
+}
+
 GetOptions("a|apname=s" => \$apname,
           "p|password=s"  => \$password,
           "i|pipe=s"  => \$pipepath,