stralloc_copyb - copy data into a stralloc

       stralloc_copyb makes sure that sa has enough space allocated to hold len bytes.  Then it copies the first
       len bytes from buf into the stralloc.

       The data that sa previously contained is overwritten and truncated.

       If  stralloc_copys  runs out of memory, stralloc_copys leaves sa alone and return 0, otherwise it returns
       1.

       stralloc_copyb - copy data into a stralloc

       1 for success, 0 on memory allocation failure.

                                                                                               stralloc_copyb(3)

#include<libowfat/stralloc.h>

       int stralloc_copyb(stralloc* sa,const char* buf,size_t len);