drcachesim: initialization interface for analysis_tool_t

Created by: snehasish

Analysis tools such as opcode_mix and view perform setup within the constructor which could fail with google internal APIs such as remote filesystems. For example, the view tool reads in the modules.log file using raw2trace_directory_t. Using a non local file path results in fatal error. To avoid similar issues we can have analysis_tool_t expose a virtual initialization method. They would be invoked by the analyzer_t after the tools have been constructed and before trace processing begins.

This issue covers

• adding an initialization interface to analysis_tool_t
• updating analyzer_t to invoke it for each analysis tool
• moving relevant initialization code for each tool to the new interface