Move string functions/utils from HAL to std/string

kernel/FastLZ/6unpack_mem.c

@@ -2,6 +2,7 @@
 #include <stddef.h>
 #include "hal/hal.h"
 #include "fastlz.h"
+#include "std/string.h"
 
 #define SIXPACK_OK                0
 #define SIXPACK_ERR_MAGIC        -1
@@ -93,7 +94,7 @@ int sixpack_decompress_mem(const uint8_t *input, size_t in_size,
         /* Stored (uncompressed) */
         if (written + size > out_cap)
           return SIXPACK_ERR_NO_SPACE;
-        hal_memcpy(output + written, chunk_data, size);
+        memcpy(output + written, chunk_data, size);
         written += size;
       } else if (opts == 1) {
         /* FastLZ compressed */