crash-manager: fix get cmd_path

crash-manager: fix get cmd_path

This commit fixes issue with report not being generated for processes
started using a relative path (e.g.: ./test-app).

In above case cmdline contained only './test-app' string and based on
that it was impossible to determine the full path to a binary.
Consequently, crash-manager assumed crashed program binary did not
exist and did not generate the report.

This commit changes the logic as follows:

  cinfo->cmd_name is read from /proc/<pid>/cmdline
  cinfo->cmd_path is read from /proc/<pid>/exe

Change-Id: If1b7557b53417d2703a81644939692fee5c801ee