delete files before symlinking; log error messages
delete files before symlinking; log error messages

The symlink() function should remove existing files before creating
symlinks, so scripts are idempotent.  Log messages when various system
calls fail (but don't make the whole script fail).

Plain-Andy/android_platform_bootable_recovery,76Demented/bootable_recovery-,InsomniaAOSP/platform_bootable_recovery,InsomniaAOSP/platform_bootable_recovery,randomblame/bootable_recovery,kylinmoddev/android_bootable_recovery,DerTeufel/dualboot_recovery,InsomniaAOSP/platform_bootable_recovery,DerTeufel/dualboot_recovery,InsomniaAOSP/platform_bootable_recovery,DerTeufel/dualboot_recovery,kylinmoddev/android_bootable_recovery,76Demented/bootable_recovery-,Plain-Andy/android_platform_bootable_recovery,DerTeufel/dualboot_recovery,kylinmoddev/android_bootable_recovery,DerTeufel/dualboot_recovery,76Demented/bootable_recovery-,randomblame/bootable_recovery,76Demented/bootable_recovery-,randomblame/bootable_recovery,Plain-Andy/android_platform_bootable_recovery,InsomniaAOSP/platform_bootable_recovery,randomblame/bootable_recovery,Plain-Andy/android_platform_bootable_recovery,randomblame/bootable_recovery,76Demented/bootable_recovery-,kylinmoddev/android_bootable_recovery