Make JP_FIRST work with JP_RTC_HZ. Bug 367675, r=dbaron

tools/jprof/README.html

@@ -64,7 +64,7 @@ which have the following meanings:
     one (with <code>kill -PROF</code>, or with <code>kill -ALRM</code> if
     JP_REALTIME is used, or with <code>kill -POLL</code> (also known as <code>kill -IO</code>) if JP_RTC_HZ is used).
 
-    <li> <b>JP_FIRST=x</b> : Wait x seconds before starting the timer.  This doesn't work with JP_RTC_HZ yet.  See <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=367675">bug 367675</a>.
+    <li> <b>JP_FIRST=x</b> : Wait x seconds before starting the timer
 
     <li> <b>JP_PERIOD=y</b> : Set timer to interrupt every y seconds.  Only
     values of y strictly greater than 0.001 are supported.

tools/jprof/stub/libmalloc.cpp

@@ -386,6 +386,8 @@ NS_EXPORT_(void) setupProfilingStuff(void)
             if (rtc) {
 #if defined(linux)
                 rtcHz = atol(rtc+10);
+                timerMiliSec = 0; /* This makes JP_FIRST work right. */
+                realTime = 1; /* It's the _R_TC and all.  ;) */
 
 #define IS_POWER_OF_TWO(x) (((x) & ((x) - 1)) == 0)
 
@@ -431,7 +433,9 @@ NS_EXPORT_(void) setupProfilingStuff(void)
                                   "profiling\n", stderr);
                             return;
                         }
-                    } else
+                    }
+
+                    if (!rtcHz || firstDelay != 0)
 #endif
                     if (realTime) {
                         sigaction(SIGALRM, &action, NULL);
@@ -459,7 +463,11 @@ NS_EXPORT_(void) setupProfilingStuff(void)
 
 		    if(startTimer) {
 #if defined(linux)
-                        if (rtcHz) {
+                        /* If we have an initial delay we can just use
+                           startSignalCounter to set up a timer to fire the
+                           first stackHook after that delay.  When that happens
+                           we'll go and switch to RTC profiling. */
+                        if (rtcHz && firstDelay == 0) {
                             puts("Jprof: enabled RTC signals");
                             enableRTCSignals(true);
                         } else