Add additional build variable checks to Android.mk files

This was causing the mm command to fail when it was run from
bootable/recovery and no crypto features had been specified in
a device's configuration files

Change-Id: Iddbeea5349bbf75cddb0250cd71821dfe3b7b9d8
diff --git a/crypto/fs_mgr/Android.mk b/crypto/fs_mgr/Android.mk
index 8834282..b2a341f 100644
--- a/crypto/fs_mgr/Android.mk
+++ b/crypto/fs_mgr/Android.mk
@@ -1,5 +1,5 @@
 # Copyright 2011 The Android Open Source Project
-
+ifeq ($(TW_INCLUDE_JB_CRYPTO), true)
 LOCAL_PATH:= $(call my-dir)
 include $(CLEAR_VARS)
 
@@ -31,3 +31,4 @@
 
 #include $(BUILD_EXECUTABLE)
 
+endif