C++17 is the default now.

Test: builds
Change-Id: I6d6438e305be9c7cf96118fc9c0b4fbcf653e052
diff --git a/Android.bp b/Android.bp
index 82bb7bd..c81e41c 100644
--- a/Android.bp
+++ b/Android.bp
@@ -49,7 +49,6 @@
 
     clang: true,
     shared_libs: ["libbase"],
-    cpp_std: "c++17",
 }
 
 cc_defaults {