Fix set of NLS translation issues

While monitoring the code, a couple of issues related to string
translation has showed up:
- Some routines for auto-updatable views return an error string, which
sometimes missed the shot.  A comment regarding string translation is
added for each routine to help with future features.
- GSSAPI authentication missed two translations.

Reported-by: Kyotaro Horiguchi
Author: Kyotaro Horiguchi
Reviewed-by: Michael Paquier, Tom Lane
Discussion: https://postgr.es/m/20180810.152131.31921918.horiguchi.kyotaro@lab.ntt.co.jp
Backpatch-through: 9.3

src/backend/commands/tablecmds.c

@@ -9041,7 +9041,7 @@ ATExecSetRelOptions(Relation rel, List *defList, AlterTableType operation,
 				ereport(ERROR,
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 						 errmsg("WITH CHECK OPTION is supported only on automatically updatable views"),
-						 errhint("%s", view_updatable_error)));
+						 errhint("%s", _(view_updatable_error))));
 		}
 	}
 

src/backend/commands/view.c

@@ -489,7 +489,7 @@ DefineView(ViewStmt *stmt, const char *queryString)
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("WITH CHECK OPTION is supported only on automatically updatable views"),
-					 errhint("%s", view_updatable_error)));
+					 errhint("%s", _(view_updatable_error))));
 	}
 
 	/*

src/backend/libpq/auth.c

@@ -751,6 +751,10 @@ static GSS_DLLIMP gss_OID GSS_C_NT_USER_NAME = &GSS_C_NT_USER_NAME_desc;
 #endif
 
 
+/*
+ * Generate an error for GSSAPI authentication.  The caller should apply
+ * _() to errmsg to make it translatable.
+ */
 static void
 pg_GSS_error(int severity, char *errmsg, OM_uint32 maj_stat, OM_uint32 min_stat)
 {
@@ -935,7 +939,7 @@ pg_GSS_recvauth(Port *port)
 		{
 			gss_delete_sec_context(&lmin_s, &port->gss->ctx, GSS_C_NO_BUFFER);
 			pg_GSS_error(ERROR,
-					   gettext_noop("accepting GSS security context failed"),
+						 _("accepting GSS security context failed"),
 						 maj_stat, min_stat);
 		}
 
@@ -961,7 +965,7 @@ pg_GSS_recvauth(Port *port)
 	maj_stat = gss_display_name(&min_stat, port->gss->name, &gbuf, NULL);
 	if (maj_stat != GSS_S_COMPLETE)
 		pg_GSS_error(ERROR,
-					 gettext_noop("retrieving GSS user name failed"),
+					 _("retrieving GSS user name failed"),
 					 maj_stat, min_stat);
 
 	/*
@@ -1025,6 +1029,11 @@ pg_GSS_recvauth(Port *port)
  *----------------------------------------------------------------
  */
 #ifdef ENABLE_SSPI
+
+/*
+ * Generate an error for SSPI authentication.  The caller should apply
+ * _() to errmsg to make it translatable.
+ */
 static void
 pg_SSPI_error(int severity, const char *errmsg, SECURITY_STATUS r)
 {

src/backend/rewrite/rewriteHandler.c

@@ -2008,6 +2008,9 @@ view_has_instead_trigger(Relation view, CmdType event)
  * is auto-updatable. Returns NULL (if the column can be updated) or a message
  * string giving the reason that it cannot be.
  *
+ * The returned string has not been translated; if it is shown as an error
+ * message, the caller should apply _() to translate it.
+ *
  * Note that the checks performed here are local to this view. We do not check
  * whether the referenced column of the underlying base relation is updatable.
  */
@@ -2047,6 +2050,9 @@ view_col_is_auto_updatable(RangeTblRef *rtr, TargetEntry *tle)
  * view_query_is_auto_updatable - test whether the specified view definition
  * represents an auto-updatable view. Returns NULL (if the view can be updated)
  * or a message string giving the reason that it cannot be.
+
+ * The returned string has not been translated; if it is shown as an error
+ * message, the caller should apply _() to translate it.
  *
  * If check_cols is true, the view is required to have at least one updatable
  * column (necessary for INSERT/UPDATE). Otherwise the view's columns are not
@@ -2183,6 +2189,9 @@ view_query_is_auto_updatable(Query *viewquery, bool check_cols)
  * required columns can be updated) or a message string giving the reason that
  * they cannot be.
  *
+ * The returned string has not been translated; if it is shown as an error
+ * message, the caller should apply _() to translate it.
+ *
  * This should be used for INSERT/UPDATE to ensure that we don't attempt to
  * assign to any non-updatable columns.
  *