tests/lapi: fix debug_torture_test

Since commit 8e35f0c ("cmake: bump luzer version")
`fdp:oneof()` in luzer API returns two values: a table's item and
it's index. This breaks test `debug_torture_test.lua` with
a message below

> bad argument #2 to 'insert' (number expected, got string)

because `fdp:one()` passed to `table.insert()` makes a call with
three arguments: table, hook mask ("string") and index ("number"),
while `table.insert()` with three arguments expects table, `pos`
("number"), and a value (any type).

Follows up #144

Author: ligurio

tests/lapi/debug_torture_test.lua

@@ -171,7 +171,8 @@ local function TestOneInput(buf)
     local n_hook_mask = fdp:consume_integer(0, #hook_mask)
     local mask = {}
     for _ = 0, n_hook_mask do
-        table.insert(mask, fdp:oneof(hook_mask))
+        local m = fdp:oneof(hook_mask)
+        table.insert(mask, m)
     end
 
     -- Turn on the hook.