Add thread usage output to lshal.

This output shows how many threads are in use at a give time.

Test: lshal, manual
Bug: 35099601
Change-Id: I3a22bb131b828cdd77e73e7810229d9c68a496d3
diff --git a/cmds/lshal/Lshal.cpp b/cmds/lshal/Lshal.cpp
index 9db42f1..e2d5f6d 100644
--- a/cmds/lshal/Lshal.cpp
+++ b/cmds/lshal/Lshal.cpp
@@ -66,7 +66,7 @@
             "        List all hals with default ordering and columns (`lshal list -ipc`)\n"
             "    lshal list [-h|--help]\n"
             "        -h, --help: Print help message for list (`lshal help list`)\n"
-            "    lshal [list] [--interface|-i] [--transport|-t] [-r|--arch]\n"
+            "    lshal [list] [--interface|-i] [--transport|-t] [-r|--arch] [-e|--threads]\n"
             "            [--pid|-p] [--address|-a] [--clients|-c] [--cmdline|-m]\n"
             "            [--sort={interface|i|pid|p}] [--init-vintf[=<output file>]]\n"
             "            [--debug|-d[=<output file>]]\n"
@@ -74,6 +74,8 @@
             "        -n, --instance: print the instance name column\n"
             "        -t, --transport: print the transport mode column\n"
             "        -r, --arch: print if the HAL is in 64-bit or 32-bit\n"
+            "        -e, --threads: print currently used/available threads\n"
+            "                       (note, available threads created lazily)\n"
             "        -p, --pid: print the server PID, or server cmdline if -m is set\n"
             "        -a, --address: print the server object address column\n"
             "        -c, --clients: print the client PIDs, or client cmdlines if -m is set\n"