RFR (XS) 8212025: Remove collector_present variable from ThreadHeapSampler

[Thomas Schatzl]

Hi,

On Wed, 2018-10-10 at 13:15 -0700, JC Beyler wrote:
> Hi all,
> 
> Here is a tiny webrev to remove the _collectors_present member that
> is now unused. I forgot to remove it when I did the fix for JDK-
> 8211950.
> 
> Webrev: http://cr.openjdk.java.net/~jcbeyler/8212025/webrev.00/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8212025
> 
> My apologies,
> Jc

  np, we are always happy about code improvements like this :)

Ship it.

Thomas