cmd/bent: log toolchain prior to compilation

Compilation may emit compilation benchmark results, so we need to log
the toolchain in use first.

For golang/go#57770.

Change-Id: Ia1fdbbabba9a556ff6be720fcd7455de23d3d147
Reviewed-on: https://go-review.googlesource.com/c/benchmarks/+/462956
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
diff --git a/cmd/bent/bent.go b/cmd/bent/bent.go
index fb411c1..67e3529 100644
--- a/cmd/bent/bent.go
+++ b/cmd/bent/bent.go
@@ -710,6 +710,7 @@
 						if config.Disabled {
 							continue
 						}
+						config.say("toolchain: " + config.Name + "\n")
 						s := todo.Configurations[ci].compileOne(&todo.Benchmarks[bi], dirs.wd, yyy)
 						if s != "" {
 							getAndBuildFailures = append(getAndBuildFailures, s)
@@ -736,6 +737,7 @@
 						if config.Disabled {
 							continue
 						}
+						config.say("toolchain: " + config.Name + "\n")
 						s := config.compileOne(&todo.Benchmarks[bi], dirs.wd, yyy)
 						if s != "" {
 							getAndBuildFailures = append(getAndBuildFailures, s)
@@ -761,6 +763,7 @@
 					if bench.Disabled || config.Disabled {
 						continue
 					}
+					config.say("toolchain: " + config.Name + "\n")
 					s := config.compileOne(bench, dirs.wd, yyy)
 					if s != "" {
 						getAndBuildFailures = append(getAndBuildFailures, s)
@@ -787,6 +790,7 @@
 				if bench.Disabled || config.Disabled {
 					continue
 				}
+				config.say("toolchain: " + config.Name + "\n")
 				s := config.compileOne(bench, dirs.wd, p.k)
 				if s != "" {
 					getAndBuildFailures = append(getAndBuildFailures, s)