test: fix pending() invocations

AFAICT busted does not report pending() invocations without the 2nd
argument.

test/functional/legacy/077_mf_hash_grow_spec.lua

@@ -15,7 +15,7 @@ describe('mf_hash_grow()', function()
 
   -- Check to see if cksum exists, otherwise skip the test
   if os.execute('which cksum 2>&1 > /dev/null') ~= 0 then
-    pending("was not tested because cksum was not found")
+    pending('was not tested because cksum was not found', function() end)
   else
     it('is working', function()
       execute('set fileformat=unix undolevels=-1')

test/functional/shell/viml_system_spec.lua

@@ -186,7 +186,7 @@ describe('system()', function()
 
   describe("with a program that doesn't close stdout", function()
     if not xclip then
-      pending('skipped (missing xclip)')
+      pending('skipped (missing xclip)', function() end)
     else
       it('will exit properly after passing input', function()
         eq('', eval([[system('xclip -i -selection clipboard', 'clip-data')]]))
@@ -365,7 +365,7 @@ describe('systemlist()', function()
 
   describe("with a program that doesn't close stdout", function()
     if not xclip then
-      pending('skipped (missing xclip)')
+      pending('skipped (missing xclip)', function() end)
     else
       it('will exit properly after passing input', function()
         eq({}, eval(

test/unit/os/fs_spec.lua

@@ -270,7 +270,7 @@ describe('fs function', function()
 
       -- Some systems may not have `id` utility.
       if (os.execute('id -G > /dev/null 2>&1') ~= 0) then
-        pending('skipped (missing `id` utility)')
+        pending('skipped (missing `id` utility)', function() end)
       else
         it('owner of a file may change the group of the file to any group of which that owner is a member', function()
           local file_gid = lfs.attributes(filename, 'gid')
@@ -296,7 +296,7 @@ describe('fs function', function()
       -- On Windows `os_fchown` always returns 0
       -- because `uv_fs_chown` is no-op on this platform.
       if (ffi.os == 'Windows' or ffi.C.geteuid() == 0) then
-        pending('skipped (os_fchown is no-op on Windows)')
+        pending('skipped (os_fchown is no-op on Windows)', function() end)
       else
         it('returns nonzero if process has not enough permissions', function()
           -- chown to root