util/superiotool: Fix build on musl-libc systems

- use __linux__ instead of __GLIBC__ guard for Linux-specific includes
- use POSIX ioperm instead of deprecated iopl

Signed-off-by: Fabian Groffen <grobian@gentoo.org>
Change-Id: I99613007aa9feddcb1041f31085cdeb195ff7a68
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73358
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <felixsinger@posteo.net>

util/superiotool/superiotool.c

@@ -323,9 +323,12 @@ int main(int argc, char *argv[])
 #if defined(__FreeBSD__)
 	if ((io_fd = open("/dev/io", O_RDWR)) < 0) {
 		perror("/dev/io");
-#else
+#elif defined(__NetBSD__)
 	if (iopl(3) < 0) {
 		perror("iopl");
+#else
+	if (ioperm(0, 6000, 1) < 0) {
+		perror("ioperm");
 #endif
 		printf("Superiotool must be run as root.\n");
 		exit(1);