Moved the memory allocator and its util functions out of the EIP712 subdirectory and gave it its own compilation flag

Also removed dead code

src_common/mem.h

@@ -0,0 +1,15 @@
+#ifndef MEM_H_
+#define MEM_H_
+
+#ifdef HAVE_DYN_MEM_ALLOC
+
+#include <stdlib.h>
+
+void    mem_init(void);
+void    mem_reset(void);
+void    *mem_alloc(size_t size);
+void    mem_dealloc(size_t size);
+
+#endif // HAVE_DYN_MEM_ALLOC
+
+#endif // MEM_H_