Make Clang plugins directory configurable for GCMole.

tools/gcmole/gcmole.lua

 -- Copyright 2011 the V8 project authors. All rights reserved.
 -- Redistribution and use in source and binary forms, with or without
 -- modification, are permitted provided that the following conditions are
 -- met:
 --
 --     * Redistributions of source code must retain the above copyright
 --       notice, this list of conditions and the following disclaimer.
 --     * Redistributions in binary form must reproduce the above
 --       copyright notice, this list of conditions and the following
 --       disclaimer in the documentation and/or other materials provided
@@ skipping 62 matching lines @@
 
 function log(...)
    io.stderr:write(string.format(...))
    io.stderr:write "\n"
 end
 
 -------------------------------------------------------------------------------
 -- Clang invocation
 
 local CLANG_BIN = os.getenv "CLANG_BIN"
+local CLANG_PLUGINS = os.getenv "CLANG_PLUGINS"
 
 if not CLANG_BIN or CLANG_BIN == "" then
    error "CLANG_BIN not set"
 end
 
+if not CLANG_PLUGINS or CLANG_PLUGINS == "" then
+   CLANG_PLUGINS = DIR
+end
+
 local function MakeClangCommandLine(plugin, plugin_args, triple, arch_define)
    if plugin_args then
      for i = 1, #plugin_args do
         plugin_args[i] = "-plugin-arg-" .. plugin .. " " .. plugin_args[i]
      end
      plugin_args = " " .. table.concat(plugin_args, " ")
    end
-   return CLANG_BIN .. "/clang -cc1 -load " .. DIR .. "/libgcmole.so"
+   return CLANG_BIN .. "/clang -cc1 -load " .. CLANG_PLUGINS .. "/libgcmole.so"
       .. " -plugin "  .. plugin
       .. (plugin_args or "")
       .. " -triple " .. triple
       .. " -D" .. arch_define
       .. " -DENABLE_DEBUGGER_SUPPORT"
       .. " -Isrc"
 end
 
 function InvokeClangPluginForEachFile(filenames, cfg, func)
    local cmd_line = MakeClangCommandLine(cfg.plugin,
@@ skipping 260 matching lines @@
 
 for _, arch in ipairs(ARCHS) do
    if not ARCHITECTURES[arch] then
       error ("Unknown arch: " .. arch)
    end
 
    errors = SafeCheckCorrectnessForArch(arch, report) or errors
 end
 
 os.exit(errors and 1 or 0)