Split up source and added basic support for different targets.

targets/_any/include/stdlib.h

@@ -0,0 +1,18 @@
+
+#pragma once
+
+#if !defined(BAD_APPLE_OS_STDLIB_H_INCLUDED)
+#define BAD_APPLE_OS_STDLIB_H_INCLUDED
+
+#include <stddef.h>
+#include "./detail/common.h"
+
+BA_EXTERN_C_BEGIN
+
+BA_CXX_NORETURN void abort();
+BA_CXX_NODISCARD void* malloc(size_t size) BA_CXX_NOEXCEPT;
+void free(void* ptr) BA_CXX_NOEXCEPT;
+
+BA_EXTERN_C_END
+
+#endif // !defined(BAD_APPLE_OS_STDLIB_H_INCLUDED)