ia64: sync with glibc headers

libc/sysdeps/linux/ia64/bits/sigcontext.h

@@ -24,6 +24,8 @@
 #ifndef _BITS_SIGCONTEXT_H
 #define _BITS_SIGCONTEXT_H 1
 
+#define __need_size_t
+#include <stddef.h>
 #include <bits/sigstack.h>
 
 struct ia64_fpreg

libc/sysdeps/linux/ia64/sys/ucontext.h

@@ -31,7 +31,7 @@
 
 typedef struct sigcontext mcontext_t;
 
-#if defined __cplusplus && __GNUC_PREREQ (3, 5)
+#if __GNUC_PREREQ (3, 5)
 # define _SC_GR0_OFFSET	\
 	__builtin_offsetof (struct sigcontext, sc_gr[0])
 #elif defined __GNUC__