Force -fPIC when compiling libcatta.

diff --git a/catta b/catta
index bb173469810e4c7de19e53793d4af2e27e6e222c..fd0cf0fc04eb828dbed5b374b2cffd9725ff4d2e 160000 (submodule)
--- a/catta
+++ b/catta
@@ -1 +1 @@
-Subproject commit bb173469810e4c7de19e53793d4af2e27e6e222c
+Subproject commit fd0cf0fc04eb828dbed5b374b2cffd9725ff4d2e