updated dotest with new test files

dotest

@@ -26,7 +26,7 @@ for i in tests-gnu/*.c; do
     cmp $i $j || die $i $j
 done
 
-for i in single-exec/*.c; do
+for i in tests-c/*.c; do
     echo $i
     j="${i%.c}.out"
     $run < $i > $j