Support priority inheritance mutex in 64bit programs.

Bug: http://b/29177606
Test: run bionic-unit-tests on walleye.
Test: run bionic-unit-tests-glibc on host.
Change-Id: Iac349284aa73515f384e7509445f87434757f59e
diff --git a/libc/libc.map.txt b/libc/libc.map.txt
index 97965ac..0960560 100644
--- a/libc/libc.map.txt
+++ b/libc/libc.map.txt
@@ -1397,6 +1397,8 @@
     posix_spawnp;
     pthread_attr_getinheritsched;
     pthread_attr_setinheritsched;
+    pthread_mutexattr_getprotocol;
+    pthread_mutexattr_setprotocol;
     pthread_setschedprio;
     sethostent;
     setnetent;