Update compiler-rt for rebase to r212749.

Includes a cherry-pick of:
r213309 - fixes umodsi3

Change-Id: Ic7367e3586b6af7ef74bee6a8cf437d5f28d975a
diff --git a/CREDITS.TXT b/CREDITS.TXT
index 4b7ef51..6964eba 100644
--- a/CREDITS.TXT
+++ b/CREDITS.TXT
@@ -23,6 +23,10 @@
 E: hhinnant@apple.com
 D: Architect and primary author of compiler-rt
 
+N: Guan-Hong Liu
+E: koviankevin@hotmail.com
+D: IEEE Quad-precision functions
+
 N: Joerg Sonnenberger
 E: joerg@NetBSD.org
 D: Maintains NetBSD port.