Revert "#14399: libgnustl.so is not present on 4.0.x devices"

This reverts commit c06e2a9065c99a7af4ec5ffdc1269c8c27fdc03a.
diff --git a/jni/Application.mk b/jni/Application.mk
index 4894e8e..8759e68 100644
--- a/jni/Application.mk
+++ b/jni/Application.mk
@@ -40,4 +40,4 @@
 APP_MODULES += libsflphone
 APP_MODULES += sflphoned
 
-APP_STL := gnustl_static
+APP_STL := gnustl_shared