hwaccess: sys/io.h is not specific to glibc

Under Linux, sys/io.h provides inb and outb, so we really need it.
However, its inclusion is conditional to the _GLIBC_ define. This is
usually OK under Linux, since both glibc and uClibc define it (uclibc
fakes being glibc).

But the mus lC library does not impersonate glibc, so we're missing
including sys/io.h in this case.

Change the include from checking _GLIBC_ to checking whether this is
Linux, looking for the __linux__ define.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

diff -durN flashrom-0.9.8.orig/hwaccess.h flashrom-0.9.8/hwaccess.h
--- flashrom-0.9.8.orig/hwaccess.h	2015-02-10 09:03:10.000000000 +0100
+++ flashrom-0.9.8/hwaccess.h	2015-10-28 20:01:54.259202484 +0100
@@ -27,7 +27,7 @@
 #include "platform.h"
 
 #if IS_X86
-#if defined(__GLIBC__)
+#if defined(__linux__)
 #include <sys/io.h>
 #endif
 #endif