sidplayall.sh: add quotes in test to avoid syntax err

Add quotes to avoid the annoying syntax error when the string is empty.
This fix is bash-specific, but we're requesting /bin/bash anyway.

Signed-off-by: Colin McCabe <cmccabe@alumni.cmu.edu>

diff --git a/sidplayall.sh b/sidplayall.sh
index 09c1488..6eec0fe 100755 (executable)
--- a/sidplayall.sh
+++ b/sidplayall.sh
@@ -25,7 +25,7 @@ done
 
 get_next_action() {
     line="?"
-    while [ $line == "?" ]; do
+    while [ "$line" == "?" ]; do
         read line
         case $line in
             "") next_file=1;;