make time-related socket options overridable by arch bits files

SO_RCVTIMEO and SO_SNDTIMEO already were, but only in aggregate with
SO_DEBUG and all of the other low/traditional options that varied per
arch. SO_TIMESTAMP* are newly overridable. the two groups have to be
done separately since mips64 and powerpc64 will override the former
but not the latter.

at some point this should be cleaned up to use bits headers more
idiomatically.

include/sys/socket.h

@@ -182,8 +182,6 @@ struct linger {
 #define SO_PEERCRED     17
 #define SO_RCVLOWAT     18
 #define SO_SNDLOWAT     19
-#define SO_RCVTIMEO     20
-#define SO_SNDTIMEO     21
 #define SO_ACCEPTCONN   30
 #define SO_PEERSEC      31
 #define SO_SNDBUFFORCE  32
@@ -192,6 +190,17 @@ struct linger {
 #define SO_DOMAIN       39
 #endif
 
+#ifndef SO_RCVTIMEO
+#define SO_RCVTIMEO     20
+#define SO_SNDTIMEO     21
+#endif
+
+#ifndef SO_TIMESTAMP
+#define SO_TIMESTAMP    29
+#define SO_TIMESTAMPNS  35
+#define SO_TIMESTAMPING 37
+#endif
+
 #define SO_SECURITY_AUTHENTICATION              22
 #define SO_SECURITY_ENCRYPTION_TRANSPORT        23
 #define SO_SECURITY_ENCRYPTION_NETWORK          24
@@ -203,14 +212,10 @@ struct linger {
 #define SO_GET_FILTER           SO_ATTACH_FILTER
 
 #define SO_PEERNAME             28
-#define SO_TIMESTAMP            29
 #define SCM_TIMESTAMP           SO_TIMESTAMP
-
 #define SO_PASSSEC              34
-#define SO_TIMESTAMPNS          35
 #define SCM_TIMESTAMPNS         SO_TIMESTAMPNS
 #define SO_MARK                 36
-#define SO_TIMESTAMPING         37
 #define SCM_TIMESTAMPING        SO_TIMESTAMPING
 #define SO_RXQ_OVFL             40
 #define SO_WIFI_STATUS          41