Fix typos.

Oskari Saarenmaa

src/bin/pg_dump/parallel.c

@@ -1262,7 +1262,7 @@ readMessageFromPipe(int fd)
 	int			ret;
 
 	/*
-	 * The problem here is that we need to deal with several possibilites: we
+	 * The problem here is that we need to deal with several possibilities: we
 	 * could receive only a partial message or several messages at once. The
 	 * caller expects us to return exactly one message however.
 	 *