[libc++abi] Build the dylib with C++17, like for libc++

GitOrigin-RevId: e3650dc97927d39a489d5a5618929dcaac7c149d
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 0503569..10300d1 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -177,7 +177,7 @@
                           CXX_EXTENSIONS
                             OFF
                           CXX_STANDARD
-                            11
+                            17
                           CXX_STANDARD_REQUIRED
                             ON
                           COMPILE_FLAGS