interceptor: consolidate the execution for execve and posix_spawn Too much code duplication accumulated, which can now be consolidated. Do that and bring back the execute() function that can now deal with a callback to the original libc method. Bug: 209401200 Signed-off-by: Matthias Maennich <[email protected]> Change-Id: I85b4c029a6a6153bbabf852cc44c03ff52d2edb1