stralloc_diffs - check if string is prefix of stralloc

       stralloc_diffs  returns  negative,  0,  or  positive, depending on whether the \0-terminated string in a,
       without the terminating \0, is lexicographically smaller than, equal  to,  or  greater  than  the  string
       stored in a.

       stralloc_diffs - check if string is prefix of stralloc

       <0 if a<b, 0 if a==b, >0 if a>b.

stralloc_diff(3), stralloc_starts(3), str_diff(3)

                                                                                               stralloc_diffs(3)

#include<libowfat/stralloc.h>

       int stralloc_diffs(stralloc* a,const char* b);