mescc: drop naive realloc.

mescc: drop naive realloc.

* mlibc/libc-gcc.c (free, memcpy): Move from libc-mes+tcc.c.
  (realloc): Use realloc from libc-mes+tcc.c
* mlibc/libc-gcc+tcc.c (free, memcpy, realloc): Remove.
* mlibc/libc-mes+tcc.c (free, memcpy, realloc): Remove.
* scaffold/tests/79-int-array.c (test): Update.
* scaffold/tests/7a-struct-char-array.c (test): Update.