Fixes tests so that they can be executed using dash as /bin/sh.

http://sourceforge.net/tracker/index.php?func=detail&aid=2125959&group_id=122858&atid=694730

--- a/tests/t_datadir

+++ b/tests/t_datadir

@@ -2,11 +2,11 @@

 unset SDCV_PAGER

 have=`../src/sdcv --data-dir ./ -l | wc -l`

-let have=have-1

+have=$(($have-1))

 ndicts=`find "${HOME}"/.stardict/dic -name "*.ifo" -print | wc -l`

-let ndicts=ndicts+1

+ndicts=$(($ndicts+1))

 if [ $have -ne $ndicts ]; then

-	let ndicts=ndicts-1

+	ndicts=$(($ndicts-1))

 	echo "test failed: sdcv says: we have: $have, but really we have: $ndicts" >&2

 	exit 1

 fi

--- a/tests/t_list

+++ b/tests/t_list

@@ -1,10 +1,10 @@

 #!/bin/sh

 ndicts=`../src/sdcv -l | wc -l`

-let ndicts=ndicts-1

+ndicts=$(($ndicts-1))

 ncom=`find /usr/share/stardict/dic -name "*.ifo" | wc -l`

 nspe=`find "${HOME}"/.stardict/dic -name "*.ifo" | wc -l`

-let nmy=ncom+nspe

+nmy=$(($ncom+$nspe))

 if [ $nmy -ne $ndicts ]; then

 	echo "should be: $nmy, we have: $ndicts" >&2

--- a/tests/t_utf8input

+++ b/tests/t_utf8input

@@ -9,13 +9,13 @@

 "

 j=0

 for i in `../src/sdcv --utf8-input -n человек 2>&1;; do

-	let j=j+1

+	j=$(($j+1))

 	if [ $j -ne 1 ]; then

 		break;

 	fi

 done

-if [ $j -eq 1 ]; then

+if [ $j -ne 1 ]; then

 	echo "empty results of search: test failed" >&2

 	exit 1

 fi