warning cleanup: GNU C++ initializer warnings.

This is the eight and final round of an effort to enable
GCC's -Wextra option. The C++ compiler, with -Wextra,
doesn't like C's universal struct initializer { 0 },
individually complaining about all the remaining members
not being initialized. What works in C++ is the { }
initializer. Conditional definition to the rescue.

* lib.h (all_zero_init): New macro which expands to
{ } under C++, and { 0 } under C.

* lib.c (make_time_impl, epoch_tm, time_string_meth,
time_parse_meth): Use all_zero_init.

* parser.c (prime_parser): Likewise.

* socket.c (sock_mark_connected): Likewise.

* sysif.c (fcntl_wrap): Likewise.

* termios.c (encode_speeds, decode_speeds): Likewise.

* configure (diag_flags): Add -Wextra.

1 files changed, 6 insertions, 0 deletions

diff --git a/lib.h b/lib.h
index b4e2554f..f039568f 100644
--- a/lib.h
+++ b/lib.h
@@ -1298,3 +1298,9 @@ loc list_collect_revappend(loc ptail, val obj);
 #define static_forward(decl) static decl
 #define static_def(def) static def
 #endif
+
+#ifdef __cplusplus
+#define all_zero_init { }
+#else
+#define all_zero_init { 0 }
+#endif