depmod: return error when index is truncated due to ENOSPC

depmod: return error when index is truncated due to ENOSPC

Before:
=======
[lucas@vader kmod]$ sudo depmod
[lucas@vader kmod]$ echo $?
0
[lucas@vader kmod]$ ls -l /lib/modules/$(uname -r)
total 12
drwxr-xr-x 8 root root   160 Jun 13 11:05 kernel
-rw-r--r-- 1 root root 12288 Jun 15 21:29 modules.alias
-rw-r--r-- 1 root root     0 Jun 15 21:29 modules.alias.bin
-rw-r--r-- 1 root root     0 Jun 15 21:29 modules.dep
-rw-r--r-- 1 root root     0 Jun 15 21:29 modules.dep.bin
-rw-r--r-- 1 root root     0 Jun 15 21:29 modules.devname
-rw-r--r-- 1 root root     0 Jun 15 21:29 modules.softdep
-rw-r--r-- 1 root root     0 Jun 15 21:29 modules.symbols
-rw-r--r-- 1 root root     0 Jun 15 21:29 modules.symbols.bin

Note that modules.alias is truncated and the other have size == 0

After:
======

[lucas@vader kmod]$ sudo ./tools/depmod
WARNING: could not open /lib/modules/3.5.0-rc2-demarchi-00028-g94fa83c/modules.order: No such file or directory
ERROR: Could not create index: output truncated: No space left on device
[lucas@vader kmod]$ echo $?
1