perfasm "perf script" invocation

[Tavian Barnes]

I suspect this might have changed in newer perf versions (otherwise it
never would have worked), but according on my computer (perf version
4.1),

$ perf script -h
...
    -F, --fields <str>    comma separated output fields prepend with
'type:'. Valid types: hw,sw,trace,raw. Fields:
comm,tid,pid,time,cpu,event,trace,ip,sym,dso,addr,symoff,period
...
    -f, --force           don't complain, do it

Therefore, I propose this patch, which fixes perfasm for me:

diff -r 29564342b418
jmh-core/src/main/java/org/openjdk/jmh/profile/LinuxPerfAsmProfiler.java
--- a/jmh-core/src/main/java/org/openjdk/jmh/profile/LinuxPerfAsmProfiler.java
 Thu Jun 25 22:31:55 2015 +0300
+++ b/jmh-core/src/main/java/org/openjdk/jmh/profile/LinuxPerfAsmProfiler.java
 Tue Jul 07 11:38:05 2015 -0400
@@ -73,7 +73,7 @@
     @Override
     protected void parseEvents() {
         try {
-            ProcessBuilder pb = new ProcessBuilder("perf", "script",
"-f", "time,event,ip,sym,dso", "-i", perfBinData);
+            ProcessBuilder pb = new ProcessBuilder("perf", "script",
"-F", "time,event,ip,sym,dso", "-i", perfBinData);
             Process p = pb.start();

             // drain streams, else we might lock up

Without it, I get:

Perf output processed (skipped 5.052 seconds):
 Column 1: cycles (0 events)
 Column 2: instructions (0 events)
...
WARNING: The perf event count is suspiciously low (0). The performance
data might be
inaccurate or misleading. Try to do the profiling again, or tune up
the sampling frequency.