Fix malloc parameter in fe-fuzz

It is fairly safe to assume that sizeof(char) will always be 1 anyway
and replace the size calculation with a comment explaining the
calculation.

src/fe-fuzz/irc/core/event-get-params.c

@@ -52,7 +52,8 @@ int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 		return 0;
 	}
 	uint8_t count = *data;
-	char *copy = malloc(sizeof(char)*(size-1+1));
+	/* malloc(size) instead of size+1, because we already used one byte of data */
+	char *copy = malloc(size);
 	memcpy(copy, data+1, size-1);
 	copy[size-1] = '\0';