[istream.unformatted] clarify boolean expression

Author: Eisenwave

source/iostreams.tex

@@ -5053,7 +5053,8 @@
 If an exception is thrown during input then
 \tcode{ios_base::badbit} is set in the local error state,
 \tcode{*this}'s error state is set to the local error state, and
-the exception is rethrown if \tcode{(exceptions() \& badbit) != 0}.
+the exception is rethrown
+if \tcode{(exceptions() \& badbit) != 0} is \keyword{true}.
 If no exception has been thrown it
 stores the number of characters extracted
 in a member object.