Initialize __abort_message_ptr in linker's copy of libc

The linker calls to __libc_fatal resulted in tombstones
with missing abort message. This commit fixes it by
initializing __abort_message_ptr for the linker's copy
of libc.

Bug: http://b/31095185
Change-Id: I883d654d7fd0ef309c80f8021202b6bfd5d5cea5

libc/bionic/libc_init_common.cpp

@@ -309,6 +309,7 @@ static void __initialize_personality() {
 
 void __libc_init_AT_SECURE(KernelArgumentBlock& args) {
   __libc_auxv = args.auxv;
+  __abort_message_ptr = args.abort_message_ptr;
 
   // Check that the kernel provided a value for AT_SECURE.
   bool found_AT_SECURE = false;