tpm_nvread.c: needs to include <sys/stat.h> for POSIX

src/tpm_mgmt/tpm_nvread.c references S_IRUSR and friends but does
not include <sys/stat.h> which defines them according to POSIX.
It builds on glibc systems because of the way the headers include one
another, but fails on uClibc and musl.

See:
[1] https://bugs.gentoo.org/show_bug.cgi?id=551440
[2] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_stat.h.html

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>

Author: Anthony G. Basile

src/tpm_mgmt/tpm_nvread.c

@@ -23,6 +23,7 @@
 #include <ctype.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "tpm_nvcommon.h"
 #include "tpm_tspi.h"