enable some core tests

test/core.lua

@@ -1,3 +1,5 @@
+config.targets = 'core'
+
 local function clean_path(p)
     -- todo: replace with dfhack.filesystem call?
     return p:gsub('\\', '/'):gsub('//', '/'):gsub('/$', '')

test/encoding.lua

@@ -1,3 +1,5 @@
+config.targets = 'core'
+
 function test.toSearchNormalized()
     expect.eq(dfhack.toSearchNormalized(''), '')
     expect.eq(dfhack.toSearchNormalized('abcd'), 'abcd')

test/test.lua

@@ -1,3 +1,5 @@
+config.targets = 'core'
+
 function test.internal_in_test()
     expect.true_(dfhack.internal.IN_TEST)
 end