test.bash: disable parallelism in verbose mode

This way we get live output, and hopefully see clearer
where things hang if they do.

Also, don't pass on flags to "go vet", the verbose output
is pretty useless.

https://github.com/rfjakob/gocryptfs/issues/625

test.bash

@@ -1,14 +1,23 @@
 #!/bin/bash
 
-if [[ -z $TMPDIR ]]; then
+set -eu
+
+VERBOSE=0
+for i in "$@" ; do
+	if [[ $i == "-v" ]] ; then
+		VERBOSE=1
+		set -x
+		break
+	fi
+done
+
+if [[ -z ${TMPDIR:-} ]]; then
 	TMPDIR=/var/tmp
 	export TMPDIR
 else
 	echo "Using TMPDIR=$TMPDIR"
 fi
 
-set -eu
-
 cd "$(dirname "$0")"
 export GO111MODULE=on
 MYNAME=$(basename "$0")
@@ -53,7 +62,7 @@ if ! go tool | grep vet > /dev/null ; then
 elif [[ -d vendor ]] ; then
 	echo "vendor directory exists, skipping 'go tool vet'"
 else
-	go vet "$@" ./...
+	go vet ./...
 fi
 
 if command -v shellcheck > /dev/null ; then
@@ -63,10 +72,18 @@ else
 	echo "shellcheck not installed - skipping"
 fi
 
+EXTRA_ARGS=""
+if [[ $VERBOSE -eq 1 ]]; then
+	# Disabling parallelism disables per-package output buffering, hence enabling
+	# live streaming of result output. And seeing where things hang.
+	EXTRA_ARGS="-p 1"
+fi
+
 #                         We don't want all the subprocesses
 #                              holding the lock file open
 #                                       vvvvv
-go test -count 1 ./... "$@" 200>&-
+# shellcheck disable=SC2086
+go test -count 1 $EXTRA_ARGS ./... "$@" 200>&-
 #       ^^^^^^^^
 #   Disable result caching