eliminate white space at ends of lines

SCCS-file: time2posix.3
SCCS-SID: 7.3

time2posix.3

@@ -42,7 +42,7 @@ passed-to functions such as
 .IR localtime(3) ,
 .IR mktime(3) ,
 and
-.IR difftime(3) . 
+.IR difftime(3) .
 However,
 POSIX gives an arithmetic
 expression for directly computing a time_t value from a given date/time,