include sys/sysmacros.h for major/minor

These functions are not part of any official spec, and glibc has always
kept them in sys/sysmacros.h.  As glibc moves to conform to POSIX, and
more alternative C libraries come up, we need to include this header
explicitly to get the prototypes.  Otherwise we fail to build like:

affinity.c: In function 'affinity_file':
affinity.c:177:7: warning: implicit declaration of function 'major' [-Wimplicit-function-declaration]
   if (major(d) != maj || minor(d) != min)
       ^
affinity.c:177:26: warning: implicit declaration of function 'minor' [-Wimplicit-function-declaration]
   if (major(d) != maj || minor(d) != min)
                          ^
./.libs/libnuma.so: undefined reference to 'minor'
./.libs/libnuma.so: undefined reference to 'major'
collect2: error: ld returned 1 exit status

See downstream bug: https://bugs.gentoo.org/580098

affinity.c

@@ -40,6 +40,7 @@
 #include <linux/rtnetlink.h>
 #include <linux/netlink.h>
 #include <sys/types.h>
+#include <sys/sysmacros.h>
 #include <ctype.h>
 #include <assert.h>
 #include <regex.h>