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.h

@@ -8,7 +8,7 @@
 #include <stdint.h>
 #include <string.h>
 #include <getopt.h>
-#if defined(__GLIBC__)
+#if defined(__linux__)
 #include <sys/io.h>
 #endif
 #if (defined(__MACH__) && defined(__APPLE__))
@@ -24,6 +24,9 @@
 # endif
 #endif
 
+#include <sys/types.h>
+#include <stdint.h>
+
 #if defined(__FreeBSD__)
 #include <sys/types.h>
 #include <machine/cpufunc.h>