Fix module_api test

test/app-tap/module_api.skipcond

 import os
 
 # skip test if .so is not found
-if not os.path.exists('app/module_api.so'):
+if not os.path.exists('app-tap/module_api.so') and \
+   not os.path.exists('app-tap/module_api.dylib'):
     self.skip=1

test/app-tap/module_api.test.lua

@@ -2,7 +2,7 @@
 
 box.cfg{logger = "tarantool.log"}
 
-package.cpath = '../app/?.so;../app/?.dylib;'..package.cpath
+package.cpath = '../app-tap/?.so;../app-tap/?.dylib;'
 
 local test = require('tap').test("module_api", function(test)
     test:plan(13)