Add a symlink at lib/libc.so.0, as expected by buildroot.

Change-Id: Ie1ecf659370a2ba1741df033603d4745c7757bee
diff --git a/arc-linux-uclibc/usr/lib/libc.so.0 b/arc-linux-uclibc/usr/lib/libc.so.0
new file mode 120000
index 0000000..88f4553
--- /dev/null
+++ b/arc-linux-uclibc/usr/lib/libc.so.0
@@ -0,0 +1 @@
+lib/libuClibc-0.9.29.so
\ No newline at end of file