[RESTRICT AUTOMERGE] SF: Call clear() instead of empty()

empty() returns bool and doesn't do anything. After upgrading libc++,
discarding the result of empty() becomes an error because the function
is marked with [[nodiscard]] in C++20 mode.

Bug: 175635923
Test: treehugger
Change-Id: I0dddc668fee3637a5e7c88925c522f04539abeba
diff --git a/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp b/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp
index 68cd45e..7a98bc2 100644
--- a/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp
+++ b/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp
@@ -359,7 +359,7 @@
 }
 
 void SurfaceInterceptorTest::blurRegionsUpdate(Transaction& t) {
-    BLUR_REGIONS_UPDATE.empty();
+    BLUR_REGIONS_UPDATE.clear();
     BLUR_REGIONS_UPDATE.push_back(BlurRegion());
     t.setBlurRegions(mBGSurfaceControl, BLUR_REGIONS_UPDATE);
 }