Arm32 dynamic function dispatch

Test: Run bionic unit test.
Test: Use gdb to make sure the right function is selected.

Change-Id: I34ccd83d472c13993f75672b1aac2b2eae65c499
diff --git a/libc/arch-arm/generic/bionic/strlen.c b/libc/arch-arm/generic/bionic/strlen.c
index 44bd72f..43d9e51 100644
--- a/libc/arch-arm/generic/bionic/strlen.c
+++ b/libc/arch-arm/generic/bionic/strlen.c
@@ -29,7 +29,7 @@
 #include <string.h>
 #include <stdint.h>
 
-size_t strlen(const char *s)
+size_t strlen_generic(const char *s)
 {
     __builtin_prefetch(s);
     __builtin_prefetch(s+32);