[build] honor --disable-rpath on darwin

skip -install_name then.
also build only world (not installables) on test_prep.
installables are still too racy.

ChangeLog

@@ -2,6 +2,7 @@
     - Build
         + Improve darwin and cygwin build, seperate installable libparrot.
           GH #1212, 1096
+        + Honor --disable-rpath on darwin, skip -install_name then
         + Update default cygwin compiler and linker to gcc with 1.7
 
 2015-11-17    release 7.10.0

config/gen/makefiles/root.in

@@ -2359,7 +2359,7 @@ t/op/testlib/test_strings.pbc: $(PARROT) t/op/testlib/test_strings.pir
 
 # Common prep for all test targets.
 # We probably need a complete build before running the tests.
-test_prep : all pbctestfiles
+test_prep : world pbctestfiles
 
 # Run test cases with a single call of t/harness. Users have to look at only
 # one report. The default set of tests to run is contained in t/harness,

config/init/hints/darwin.pm

@@ -88,15 +88,20 @@ sub runstep {
         libparrot_shared       => "libparrot.$version$share_ext",
         libparrot_shared_alias => "libparrot$share_ext",
         rpath                  => "-L",
-        inst_libparrot_soname       => "-install_name "
+        inst_libparrot_soname  => "-install_name "
             . '"'
             . $conf->data->get('libdir')
             . '/libparrot'
             . $conf->data->get('share_ext')
             . '"',
         libparrot_soname       => "-install_name \"$lib_dir/libparrot.$version$share_ext\""
-    );
+                            );
     $darwin_selections{dynext_dirs} = $flags->{dynext_dirs} if $flags->{dynext_dirs};
+    if ( $conf->options->get('disable-rpath') ) {
+        $darwin_selections{inst_libparrot_soname} = '';
+        $darwin_selections{libparrot_soname} = '';
+    }
+
     my $darwin_hints = "Darwin hints settings:\n";
     for my $k (sort keys %darwin_selections) {
         $darwin_hints .= sprintf("  %-24s => %s\n" => (