alloc-util: drop _alloc_(2, 3) decorator from memdup_suffix0_multiply()

This decorator tells compilers that the memory we return is shorter than
it actually is, thus triggering misleading bad memory access complaints.

Fixes: #13026

src/basic/alloc-util.h

@@ -112,7 +112,9 @@ _alloc_(2, 3) static inline void *memdup_multiply(const void *p, size_t size, si
         return memdup(p, size * need);
 }
 
-_alloc_(2, 3) static inline void *memdup_suffix0_multiply(const void *p, size_t size, size_t need) {
+/* Note that we can't decorate this function with _alloc_() since the returned memory area is one byte larger
+ * than the product of its parameters. */
+static inline void *memdup_suffix0_multiply(const void *p, size_t size, size_t need) {
         if (size_multiply_overflow(size, need))
                 return NULL;