* libc/machine/spu/straddr.h: New file, supplies _straddr.
* libc/machine/spu/strcat.c: Use _straddr and _strcpy.
* libc/machine/spu/strcpy.c: Use _strcpy.
* libc/machine/spu/strcpy.h: Supply _strcpy for optimized SPU
str[n]cpy and str[n]cat.
* libc/machine/spu/strncat.c: Use _straddr and _strcpy.
* libc/machine/spu/strncpy.c: Use _strcpy.