Add quotes (fbsd sh needs them) and check if the command can be executed

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@7982 d0543943-73ff-0310-b7d9-9358b9ac24b2

build/getsounds.sh.in

@@ -7,10 +7,10 @@ CURL=@CURL@
 
 DIR=`pwd`
 
-if [ -f $WGET ] ; then
+if [ -x "$WGET" ] ; then
     DOWNLOAD_CMD=$WGET
 else
-    if [ -f $CURL ] ; then
+    if [ -x "$CURL" ] ; then
         DOWNLOAD_CMD="$CURL -O"
     fi
 fi