ninjabackend: use an unordered set for NinjaBuildElement

The deps and orderdeps are sorted on output, so there is no need to preserve
their order.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Eli Schwartz <eschwartz93@gmail.com>

mesonbuild/backend/ninjabackend.py

@@ -323,8 +323,8 @@ class NinjaBuildElement:
             self.infilenames = [infilenames]
         else:
             self.infilenames = infilenames
-        self.deps = OrderedSet()
+        self.deps = set()
-        self.orderdeps = OrderedSet()
+        self.orderdeps = set()
         self.elems = []
         self.all_outputs = all_outputs
         self.output_errors = ''