_FORTIFY_SOURCE: move a declaration to its sole call site.

Change-Id: If491319c9cf960703054ab7685f5d6eb266167bf
diff --git a/libc/include/bits/fortify/string.h b/libc/include/bits/fortify/string.h
index 6f0ee4a..0b4b70b 100644
--- a/libc/include/bits/fortify/string.h
+++ b/libc/include/bits/fortify/string.h
@@ -42,7 +42,6 @@
 size_t __strlcat_chk(char* _Nonnull, const char* _Nonnull, size_t, size_t);
 
 #if defined(__BIONIC_FORTIFY)
-void* _Nullable __memrchr_real(const void* _Nonnull, int, size_t) __RENAME(memrchr);
 
 #if __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
 /* No diag -- clang diagnoses misuses of this on its own.  */
@@ -153,6 +152,8 @@
     return __memchr_chk(s, c, n, bos);
 }
 
+void* _Nullable __memrchr_real(const void* _Nonnull, int, size_t) __RENAME(memrchr);
+
 __BIONIC_FORTIFY_INLINE
 void* _Nullable __memrchr_fortify(const void* _Nonnull const __pass_object_size s, int c, size_t n) __overloadable {
     size_t bos = __bos(s);