internal/rosa: libffi artifact

Required by python during llvm test suite.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/python.go

@@ -36,6 +36,7 @@ func (t Toolchain) NewPython() pkg.Artifact {
 	return t.New("python-"+version, []pkg.Artifact{
 		t.NewMake(),
 		t.NewZlib(),
+		t.NewLibffi(),
 	}, nil, []string{
 		"EXTRATESTOPTS=-j0 -x " + strings.Join(skipTests, " -x "),
 	}, `