Make the bionic tests implicitly test bionic's shadow call stack support.

For the moment this is an internal-only change until the AOSP kernels
can be fixed to not clobber x18.

Bug: 112907825
Change-Id: I4442ad424539e5054a3489451d1b8ab522af0a3e
diff --git a/tests/Android.bp b/tests/Android.bp
index 6a644b6..b1a73dc 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -38,6 +38,12 @@
         // For glibc.
         "-D__STDC_LIMIT_MACROS",
     ],
+    // Make the bionic tests implicitly test bionic's shadow call stack support.
+    arch: {
+        arm64: {
+           cflags: ["-fsanitize=shadow-call-stack"],
+        },
+    },
     stl: "libc++",
     sanitize: {
         never: true,