Add the dl_iterate_phdr function to libdl for arm.

Bug: 8410085

Merge from internal master.

(cherry-picked from cb491bc66dc0abc145930b09086eb9189a30f6c2)

Change-Id: I94ed51bc5d4c626df7552c0e85c31ccee2d6568f
diff --git a/libdl/libdl.c b/libdl/libdl.c
index 378f521..548364c 100644
--- a/libdl/libdl.c
+++ b/libdl/libdl.c
@@ -30,12 +30,8 @@
 
 void *dl_unwind_find_exidx(void *pc, int *pcount) { return 0; }
 
-#elif defined(__i386__) || defined(__mips__)
+#endif
 
 /* we munge the cb definition so we don't have to include any headers here.
  * It won't affect anything since these are just symbols anyway */
 int dl_iterate_phdr(int (*cb)(void *info, void *size, void *data), void *data) { return 0; }
-
-#else
-#error Unsupported architecture. Only mips, arm and x86 are supported.
-#endif