sunrpc: convert to time64_t for expiry

Using signed 32-bit types for UTC time leads to the y2038 overflow,
which is what happens in the sunrpc code at the moment.

This changes the sunrpc code over to use time64_t where possible.
The one exception is the gss_import_v{1,2}_context() function for
kerberos5, which uses 32-bit timestamps in the protocol. Here,
we can at least treat the numbers as 'unsigned', which extends the
range from 2038 to 2106.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

net/sunrpc/auth_gss/svcauth_gss.c

@@ -436,7 +436,7 @@ static int rsc_parse(struct cache_detail *cd,
 	int id;
 	int len, rv;
 	struct rsc rsci, *rscp = NULL;
-	time_t expiry;
+	time64_t expiry;
 	int status = -EINVAL;
 	struct gss_api_mech *gm = NULL;
 
@@ -1221,7 +1221,7 @@ static int gss_proxy_save_rsc(struct cache_detail *cd,
 	static atomic64_t ctxhctr;
 	long long ctxh;
 	struct gss_api_mech *gm = NULL;
-	time_t expiry;
+	time64_t expiry;
 	int status = -EINVAL;
 
 	memset(&rsci, 0, sizeof(rsci));