Fix file reading and move it into a function

There were a few problems with the previous implementation:

- the `fread` call was wrong, reading too much data
- the buffer was not `memset` prior to reading

c/jsc-test.c

JSStringRef to_string(JSContextRef ctx, JSValueRef val);
JSValueRef evaluate_script(JSContextRef ctx, char *script, char *source);
char* get_contents(char *path);
JSValueRef function_console_log(JSContextRef ctx, JSObjectRef function, JSObjectRef thisObject, size_t argumentCount, const JSValueRef arguments[], JSValueRef* exception) {
	for (int i = 0; i < argumentCount; i++) {
		if (i > 0) {
		JSStringGetUTF8CString(path_str_ref, path, 100);
		JSStringRelease(path_str_ref);
		FILE *f = fopen(path, "r");
		if (f == NULL) {
			perror("fopen");
			goto err;
		}
		struct stat f_stat;
		if (fstat(fileno(f), &f_stat) < 0) {
			perror("fstat");
			goto err;
		}
		char *buf = malloc(f_stat.st_size * sizeof(char));
		fread(buf, sizeof(char), f_stat.st_size, f);
		if (ferror(f)) {
			perror("fread");
			free(buf);
		char full_path[150];
		snprintf(full_path, 150, "%s/%s", "out", path);
		char *buf = get_contents(full_path);
		if (buf == NULL) {
			goto err;
		}
		evaluate_script(ctx, buf, path);
		evaluate_script(ctx, buf, full_path);
		free(buf);
	}
	return val;
}
char *get_contents(char *path) {
	FILE *f = fopen(path, "r");
	if (f == NULL) {
		perror("fopen");
		goto err;
	}
	struct stat f_stat;
	if (fstat(fileno(f), &f_stat) < 0) {
		perror("fstat");
		goto err;
	}
	char *buf = malloc(f_stat.st_size);
	memset(buf, 0, f_stat.st_size);
	fread(buf, f_stat.st_size, 1, f);
	buf[f_stat.st_size] = '\0';
	if (ferror(f)) {
		perror("fread");
		free(buf);
		goto err;
	}
	if (fclose(f) < 0) {
		perror("fclose");
		goto err;
	}
	return buf;
err:
	return NULL;
}