Set default pool when RBE or goma is enabled

Pass --default_pool=local_pool to kati when RBE or goma is enabled
to put most rules into the local_pool.  Specific rules that support
RBE or goma will set .KATI_NINJA_POOL := none to remove themselves
from the local_pool.  Passing --default_pool will also disable the
hack in kati that sets the pool based on the presence of the string
"/gomacc" in the command line.

Fixes: 143938974
Test: inspect pools in build-${TARGET-PRODUCT}.ninja for m USE_RBE=true
Test: inspect pools in build-${TARGET-PRODUCT}.ninja for m USE_GOMA=true
Change-Id: I839b2488383fcd63fffd613e25b0b9abcb72b567

ui/build/config.go

@@ -767,6 +767,10 @@ func (c *configImpl) StartRBE() bool {
 	return true
 }
 
+func (c *configImpl) UseRemoteBuild() bool {
+	return c.UseGoma() || c.UseRBE()
+}
+
 // RemoteParallel controls how many remote jobs (i.e., commands which contain
 // gomacc) are run in parallel.  Note the parallelism of all other jobs is
 // still limited by Parallel()

ui/build/kati.go

@@ -89,6 +89,10 @@ func runKati(ctx Context, config Config, extraSuffix string, args []string, envF
 		args = append(args, "--empty_ninja_file")
 	}
 
+	if config.UseRemoteBuild() {
+		args = append(args, "--default_pool=local_pool")
+	}
+
 	cmd := Command(ctx, config, "ckati", executable, args...)
 	cmd.Sandbox = katiSandbox
 	pipe, err := cmd.StdoutPipe()

ui/build/ninja.go

@@ -43,7 +43,7 @@ func runNinja(ctx Context, config Config) {
 	args = append(args, config.NinjaArgs()...)
 
 	var parallel int
-	if config.UseGoma() || config.UseRBE() {
+	if config.UseRemoteBuild() {
 		parallel = config.RemoteParallel()
 	} else {
 		parallel = config.Parallel()