Added hashset declaration

src/hashset.asm

@@ -0,0 +1,23 @@
+; struct Allocator {
+;     alloc: (U32) -> ptr
+;     realloc: (ptr, U32) -> ptr
+;     free: (ptr) -> ()
+; }
+;
+
+; Creates a hashset for the specified allocator, hash function and equality function
+; Arguments:
+; r1 - The pointer to the allocator
+; r2 - The hash function
+; r3 - The equality function
+; r4 - The hash function context
+; r5 - The equality function context
+; Result:
+; r1 - The pointer to the hashset structure
+; Info:
+; The hash function should follow the stdlib calling convention
+; The hash function receives one argument (the value of the item) and should return an integer which remains the same for the lifetime of the value.
+; The equality function should follow the stdlib calling convention
+; The equality function receives two arguments (the value of the two items) and should return either a zero (when the items are not equal) or any other value (if they are equal).
+pub new_hashset:
+