Intercept native cross-module calls with -native_exec_retakeover

This only works for modules with PLT relocations that are resolved lazily, and
therefore call through the resolver inserted in the previous diff.  The
interceptor currently just logs.  Eventually it will begin interpreting from
the target PC.

The special heap stubs cause a leak curiosity when -native_exec_retakeover is
enabled.  This will be fixed in a forthcoming CL which knows how to remove the
PLT hooks.

Review URL: https://codereview.appspot.com/7306048

git-svn-id: https://dynamorio.googlecode.com/svn/trunk@1890 49cc7528-f6fd-11dd-9d1a-b59b2e1864b6
Make drrun_exe on Linux use LD_PRELOAD injection by default

This is needed to replace the drrun script.  The injector now reads the
DR's options in the config file to decide if it should use early
injection or LD_PRELOAD injection.  The drrun frontend accepts the
-early argument for compatibility with the script and simply forwards
-early_inject through to DR's options.

Review URL: https://codereview.appspot.com/7313044

git-svn-id: https://dynamorio.googlecode.com/svn/trunk@1891 49cc7528-f6fd-11dd-9d1a-b59b2e1864b6