libui: Add std::hash support for Rects/Region

Adds support for std::hash to Rect, FloatRect, and Region.

Bug: 158790260
Test: libui unit tests
Change-Id: I593bad1d3111d9b28984de5c2d80695c124e30b6
diff --git a/libs/ui/tests/Rect_test.cpp b/libs/ui/tests/Rect_test.cpp
index 5499a5b..9cc36bb 100644
--- a/libs/ui/tests/Rect_test.cpp
+++ b/libs/ui/tests/Rect_test.cpp
@@ -259,4 +259,33 @@
     EXPECT_EQ(FloatRect(10.f, 20.f, 50.f, 60.f), floatRect);
 }
 
+TEST(RectTest, RectHash) {
+    const std::vector<Rect> rects = {
+            Rect(10, 20, 50, 60), Rect(11, 20, 50, 60), Rect(11, 21, 50, 60),
+            Rect(11, 21, 51, 60), Rect(11, 21, 51, 61),
+    };
+
+    for (const auto& a : rects) {
+        for (const auto& b : rects) {
+            const bool hashEq = std::hash<Rect>{}(a) == std::hash<Rect>{}(b);
+            EXPECT_EQ(a == b, hashEq);
+        }
+    }
+}
+
+TEST(RectTest, FloatRectHash) {
+    const std::vector<FloatRect> floatRects = {
+            Rect(10, 20, 50, 60).toFloatRect(), Rect(11, 20, 50, 60).toFloatRect(),
+            Rect(11, 21, 50, 60).toFloatRect(), Rect(11, 21, 51, 60).toFloatRect(),
+            Rect(11, 21, 51, 61).toFloatRect(),
+    };
+
+    for (const auto& a : floatRects) {
+        for (const auto& b : floatRects) {
+            const bool hashEq = std::hash<FloatRect>{}(a) == std::hash<FloatRect>{}(b);
+            EXPECT_EQ(a == b, hashEq);
+        }
+    }
+}
+
 } // namespace android::ui