[scripts/build] Include timestamps in logs by enabling Bash tracing

Example log line:

```
+ 2019-11-17 17:49:34+00:00 make -j 2 target-files-package brillo_update_payload
```

Author: ypid

scripts/build

@@ -72,7 +72,7 @@ function build_external(){
 function build_platform(){
 	cd "$base_dir"
 	choosecombo "${build_type}" "aosp_${device}" "${build_variant}"
-	make -j "${cores}" target-files-package brillo_update_payload
+	(set -o xtrace; make -j "${cores}" target-files-package brillo_update_payload)
 	cd -
 }
 

scripts/environment

@@ -48,7 +48,8 @@ environment = {
         strftime('%m%d%H%M', gmtime(config['datetime'])),
     "KCONFIG_NOTIMESTAMP": 1,
     "RANDFILE": "%s/randfile.bin" % base_dir,
-    "LC_ALL":"C"
+    "LC_ALL":"C",
+    "PS4": '+ $(date --rfc-3339=seconds) ',
 }
 
 environment['BUILD_KERNEL'] = "true"

scripts/retry

@@ -1,7 +1,7 @@
 #!/bin/bash
 ## Credits go to Samuel `sj26` Cochran, ref: https://gist.github.com/sj26/88e1c6584397bb7c13bd11108a579746
 
-set -o nounset -o pipefail -o errexit;
+set -o nounset -o pipefail -o errexit
 
 [[ $# -le 1 ]] && { echo "Usage $0 <retry_number> <command>"; }