[ostream.formatted.reqmts],[ostream.unformatted] "that object" not "this object"

Avoid saying "this object" when not talking about `*this`.

Author: jwakely

source/iostreams.tex

@@ -6248,7 +6248,7 @@
 \pnum
 Each formatted output function begins execution by constructing an object of class
 \tcode{sentry}.
-If this object returns
+If that object returns
 \tcode{true}
 when converted to a value of type
 \tcode{bool},
@@ -6664,7 +6664,7 @@
 unformatted
 output function begins execution by constructing an object of class
 \tcode{sentry}.
-If this object returns
+If that object returns
 \tcode{true},
 while converting to a value of type
 \tcode{bool},
@@ -6766,7 +6766,7 @@
 If
 \tcode{rdbuf()}
 is not a null pointer,
-constructs a sentry object. If this object returns \tcode{true} when converted to a value of type \tcode{bool} the function
+constructs a sentry object. If that object returns \tcode{true} when converted to a value of type \tcode{bool} the function
 calls
 \tcode{rdbuf()->pubsync()}.
 If that function returns -1