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-malloc-0-null.h

@@ -0,0 +1,22 @@
+/* mbedtls_config.h modifier that forces calloc(0) to return NULL.
+ * Used for testing.
+ */
+/*
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#include <stdlib.h>
+
+#ifndef MBEDTLS_PLATFORM_STD_CALLOC
+static inline void *custom_calloc(size_t nmemb, size_t size)
+{
+    if (nmemb == 0 || size == 0) {
+        return NULL;
+    }
+    return calloc(nmemb, size);
+}
+
+#define MBEDTLS_PLATFORM_MEMORY
+#define MBEDTLS_PLATFORM_STD_CALLOC custom_calloc
+#endif