guarantee current-inexact-milliseconds as since Jan 1, 1970

svn: r17343

collects/scribblings/reference/time.scrbl

@@ -68,8 +68,8 @@ time.}
 
 @defproc[(current-inexact-milliseconds) real?]{
 
-Like @scheme[current-milliseconds], but the result never decreases
-(until the machine is turned off).}
+Returns the current time in milliseconds since midnight UTC, January
+1, 1970.}
 
 
 @defproc[(current-process-milliseconds [thread (or/c thread? #f)]) 

src/mzscheme/src/fun.c

@@ -8102,6 +8102,7 @@ double scheme_get_inexact_milliseconds(void)
 {
 #ifdef USE_MACTIME
   {
+    /* This is wrong, since it's not since January 1, 1970 */
     UnsignedWide time;
     Microseconds(&time);
     return (((double)(time.lo >> 10)