wscript: use internal and install name ARDOUR_NAME configurable

wscript

@@ -792,6 +792,8 @@ def options(opt):
     autowaf.set_options(opt, debug_by_default=True)
     opt.add_option('--program-name', type='string', action='store', default='Ardour', dest='program_name',
                     help='The user-visible name of the program being built')
+    opt.add_option('--internal-name', type='string', action='store', default='ardour', dest='internal_name',
+                    help='The internal name of the program being built, like ardour7')
     opt.add_option('--arch', type='string', action='store', dest='arch',
                     help='Architecture-specific compiler FLAGS')
     opt.add_option('--with-backends', type='string', action='store', default='', dest='with_backends',
@@ -962,7 +964,7 @@ def configure(conf):
     conf.env['MAJOR'] = MAJOR
     conf.env['MINOR'] = MINOR
     conf.env['MICRO'] = MICRO
-    conf.env['ARDOUR_NAME'] = 'ardour' + MAJOR
+    conf.env['ARDOUR_NAME'] = Options.options.internal_name
     conf.line_just = 52
     autowaf.set_recursive()
     autowaf.configure(conf)