Use C99 designated initializers in a couple places

Some portions of libhcrypto are reused by other projects in
diverse environments, including within operating system kernel modules.
In some such build environments, hardening measures such as grsecurity
can (randomly) reorder structure elements, so as to make it harder
for an attacker to determine the offset from a known field's address
to a different field that is needed for an attack.

However, doing so requires the use of C99 designated initializers
to make the source code compatible with such structure rearrangement,
as opposed to the "traditional" C aggregate type initializers, which
just list fields in order.  This feature is also available as a
GCC extension since early versions of GCC.  However, it is not
provided by many common versions of visual studio (and presumably
also not by the vendor compiler for various commercial Unixes),
so the traditional initializers must remain, behind a conditional.
__GNUC__ or __STDC_VERSION__ >= 199901 should be enough to get
most cases with support for designated initializers, at least
for now.

Signed-off-by: Nicolas Williams <nico@twosigma.com>

lib/hcrypto/rand-timer.c

@@ -183,6 +183,16 @@ timer_status(void)
 #endif
 }
 
+#if defined(__GUNC__) || (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901)
+const RAND_METHOD hc_rand_timer_method = {
+    .seed = timer_seed,
+    .bytes = timer_bytes,
+    .cleanup = timer_cleanup,
+    .add = timer_add,
+    .pseudorand = timer_pseudorand,
+    .status = timer_status
+};
+#else
 const RAND_METHOD hc_rand_timer_method = {
     timer_seed,
     timer_bytes,
@@ -191,6 +201,7 @@ const RAND_METHOD hc_rand_timer_method = {
     timer_pseudorand,
     timer_status
 };
+#endif
 
 const RAND_METHOD *
 RAND_timer_method(void)