init: use full command for exec services' names

Before:
init: starting service 'exec 4 (/system/bin/vdc)'...
init: starting service 'exec 5 (/system/bin/tzdatacheck)'...
init: starting service 'exec 6 (/system/bin/bootstat)'...
init: starting service 'exec 7 (/system/bin/bootstat)'...

After:
init: starting service 'exec 4 (/system/bin/vdc --wait cryptfs mountdefaultencrypted)'...
init: starting service 'exec 5 (/system/bin/tzdatacheck /system/usr/share/zoneinfo /data/misc/zoneinfo)'...
init: starting service 'exec 6 (/system/bin/bootstat -r post_decrypt_time_elapsed)'...
init: starting service 'exec 7 (/system/bin/bootstat --record_boot_complete)'...

Test: Boot bullhead, observe above logging change
Change-Id: I59e2bd9e3d341bbed9537c972e47246d0a12769d