Fix some c99 struct initializer uninitialized member warnings

that clang detects and GCC misses.

src/arp.c

@@ -109,7 +109,7 @@ struct arp_data {
 static struct arp_data garp = {
     .state = AS_NONE,
     .wake_ts = { -1, -1, -1, -1, -1 },
-    .send_stats = {{0},{0},{0}},
+    .send_stats = {{0,0},{0,0},{0,0}},
     .last_conflict_ts = 0,
     .gw_check_initpings = 0,
     .arp_check_start_ts = 0,

src/ndhc.c

@@ -186,7 +186,8 @@ static void setup_signals_ndhc(void)
 
 static void signal_dispatch(void)
 {
-    struct signalfd_siginfo si = {0};
+    struct signalfd_siginfo si;
+    memset(&si, 0, sizeof si);
     ssize_t r = safe_read(cs.signalFd, (char *)&si, sizeof si);
     if (r < 0) {
         log_error("%s: ndhc: error reading from signalfd: %s",

src/sys.c

@@ -77,7 +77,8 @@ int setup_signals_subprocess(void)
 
 void signal_dispatch_subprocess(int sfd, const char pname[static 1])
 {
-    struct signalfd_siginfo si = {0};
+    struct signalfd_siginfo si;
+    memset(&si, 0, sizeof si);
     ssize_t r = safe_read(sfd, (char *)&si, sizeof si);
     if (r < 0) {
         log_error("%s: %s: error reading from signalfd: %s",