Reland ifuncs for strcmp and strlen.

This reverts commit e4788d4c7e842b0ca24363ebc5544a16c9e3b185,
which undid this change during the Q betas.

Bug: http://b/120989619

(cherry picked from commit 927fe99692b1edc723e74bfc17ed718a84ddc6fd)

Change-Id: Ie8fc0fc0965055f312c2c0cc0f64adb7594ffdb4
diff --git a/libc/Android.bp b/libc/Android.bp
index 23ccbe3..32e7560 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -1435,12 +1435,7 @@
             srcs: ["arch-x86/dynamic_function_dispatch.cpp"],
         },
         arm: {
-            srcs: [
-                "arch-arm/dynamic_function_dispatch.cpp",
-
-                // Workaround for b/120254692.
-                "arch-arm/dynamic_function_wrapper.S",
-            ],
+            srcs: ["arch-arm/dynamic_function_dispatch.cpp"],
         },
     },