Shallow argument inspection for execve

Shallow argument inspection for execve

It would even be handy if argv[k] could be readily inspected during the LSM processing for execve. Today this is possible but cumbersome using tomoyo_security. Instead, remove_arg_zero() in fs/exec.c could return into a buffer what it removed. The entire argv[] could be restored by remembering and resetting the original string pointer and count before any calls to remove_arg_zero().