Assorted changes wrt. gRPC client/server comms:

- Actually make it work again (commit 00cfb7df61b1f3d9fac8ee29d92b315cbfe6d28f broke it, maybe I shouldn't send out changes in a hurry next time)
- Rename --grpc_port to --command_port (it's a bit better name)
- Do not send a kill signal to the server that can't be connected if we only connect to it to verify its presence

--
MOS_MIGRATED_REVID=120418784

src/main/cpp/blaze_startup_options_common.cc

diff --git a/src/main/cpp/blaze_startup_options_common.cc b/src/main/cpp/blaze_startup_options_common.cc
index 54a6499..a518bd5 100644
--- a/src/main/cpp/blaze_startup_options_common.cc
+++ b/src/main/cpp/blaze_startup_options_common.cc
@@ -50,7 +50,7 @@
   // 3 hours (but only 5 seconds if used within a test)
   max_idle_secs = testing ? 5 : (3 * 3600);
   oom_more_eagerly_threshold = 100;
-  grpc_port = -1;
+  command_port = -1;
   oom_more_eagerly = false;
   watchfs = false;
   invocation_policy = NULL;
@@ -81,7 +81,7 @@
   lhs->batch_cpu_scheduling = rhs.batch_cpu_scheduling;
   lhs->io_nice_level = rhs.io_nice_level;
   lhs->max_idle_secs = rhs.max_idle_secs;
-  lhs->grpc_port = rhs.grpc_port;
+  lhs->command_port = rhs.command_port;
   lhs->oom_more_eagerly = rhs.oom_more_eagerly;
   lhs->watchfs = rhs.watchfs;
   lhs->allow_configurable_attributes = rhs.allow_configurable_attributes;
@@ -233,11 +233,11 @@
     watchfs = false;
     option_sources["watchfs"] = rcfile;
   } else if ((value = GetUnaryOption(
-      arg, next_arg, "--grpc_port")) != NULL) {
-    if (!blaze_util::safe_strto32(value, &grpc_port) ||
-        grpc_port < -1 || grpc_port > 65535) {
+      arg, next_arg, "--command_port")) != NULL) {
+    if (!blaze_util::safe_strto32(value, &command_port) ||
+        command_port < -1 || command_port > 65535) {
       blaze_util::StringPrintf(error,
-          "Invalid argument to --grpc_port: '%s'. "
+          "Invalid argument to --command_port: '%s'. "
           "Must be a valid port number or -1 to disable the gRPC server.\n",
           value);
       return blaze_exit_code::BAD_ARGV;