Solaris (and illumos) have no /proc/%d/task/

[mtelka]

I noticed that on illumos the ThreadLister is compiled in (tested with GCC 10.4.0), but the /proc/%d/task/ directory it not provided by procfs there. I suggest to change the condition at line 979 from:

#if !SANITIZER_NETBSD

to

#if !SANITIZER_NETBSD && !SANITIZER_SOLARIS

or maybe even to

#if SANITIZER_LINUX

because I suspect the /proc/%d/task/ directory is Linux-only.