Determining if one string occurs at the end of another
Const correct the pointers. The function is not changing anything in memory, no reason they shouldn't be const. Same with variables you declare in the function; Make them const

int strend(const char* s, const char* t)


Check for NULL in the input pointers.

Use library string functions wherever possible.
Instead of doing:

while(*s++) ;
s-=2;


call strlen(s); and then substract 1 as needed in your algo. Since you are iterating over the string anyway replacing this with a function call has the same efficiency and makes it more readable.

Add { around the while loop. It is future-proof.

Unit-test to confirm correctness.