Revert "Revert "Remove limit of system property name length""

This reverts commit 489f58b5eaedd5a80635bb3a7b39e97037c585f6.
Bug: http://b/33926793
Bug: http://b/34670529
Test: Run bionic-unit-tests --gtest_filter=prop*

Change-Id: Id4e94652dc2310a21f5b7bd3af098bf79df3f380
diff --git a/libc/libc.arm.map b/libc/libc.arm.map
index 3ff7ead..4319429 100644
--- a/libc/libc.arm.map
+++ b/libc/libc.arm.map
@@ -1265,6 +1265,7 @@
 
 LIBC_O {
   global:
+    __system_property_read_callback; # future
     bsd_signal; # arm x86 mips versioned=26
     catclose; # future
     catgets; # future