Support for PC platform (#12)

* improvements for cross-platform compiling

* moved tactility-core to libs/

* splitup improvements

* remove git/gitmodules from freertos

* better platformbetter platform checks

* added build scripts

* delete mbedtls

* re-add mbedtls

* fixes and improvements

* added pc build

* simplify build scripts

* revert build scrpit

* updated builds

* fix for pc

* fix for pc

* fix for build

libs/mbedtls/tests/configs/user-config-zeroize-memset.h

@@ -0,0 +1,17 @@
+/* mbedtls_config.h modifier that defines mbedtls_platform_zeroize() to be
+ * memset(), so that the compile can check arguments for us.
+ * Used for testing.
+ */
+/*
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#include <string.h>
+
+/* Define _ALT so we don't get the built-in implementation. The test code will
+ * also need to define MBEDTLS_TEST_DEFINES_ZEROIZE so we don't get the
+ * declaration. */
+#define MBEDTLS_PLATFORM_ZEROIZE_ALT
+
+#define mbedtls_platform_zeroize(buf, len) memset(buf, 0, len)