SafeStack: Add #include of <stdint.h>.

Should fix the FreeBSD build.

llvm-svn: 240555
diff --git a/compiler-rt/lib/safestack/safestack.cc b/compiler-rt/lib/safestack/safestack.cc
index 6e1d00b..0e52c2a 100644
--- a/compiler-rt/lib/safestack/safestack.cc
+++ b/compiler-rt/lib/safestack/safestack.cc
@@ -17,6 +17,7 @@
 #include <limits.h>
 #include <pthread.h>
 #include <stddef.h>
+#include <stdint.h>
 #include <sys/resource.h>
 #include <sys/user.h>