Update libc

This brings in powerpc64 and powerpc64le support recently added.

diff --git a/src/liblibc b/src/liblibc
index 95d6a00134f284e6b889d98f4c2cb4b285950327..9aa6600bd8f4e4f370a7d2fb76c4b3efc669cadf 160000 (submodule)
--- a/src/liblibc
+++ b/src/liblibc
@@ -1 +1 @@
-Subproject commit 95d6a00134f284e6b889d98f4c2cb4b285950327
+Subproject commit 9aa6600bd8f4e4f370a7d2fb76c4b3efc669cadf