usr_bin/soundtest: Fix a couple of shellcheck warnings

- SC2046: Quote this to prevent word splitting.
- SC2230: which is non-standard. Use builtin 'command -v' instead.

diff --git a/usr_bin/soundtest b/usr_bin/soundtest
index 6146df7..dc57bf3 100755 (executable)
--- a/usr_bin/soundtest
+++ b/usr_bin/soundtest
@@ -6,7 +6,7 @@
 # License:       This file is licensed under the GPL v2.
 ################################################################################
 
-if ! [ $(which speaker-test) ] ; then
+if ! [ "$(command -v speaker-test)" ] ; then
   echo "Sorry, speaker-test (from alsa-utils) not available.">&2
   exit 1
 fi