ignored mmap errors

[ael-code]

errors raised on mmap calls on allocator initialization are ignored:

error stack trace:

• mmap - src/mm/allocator.c:63
• allocate_pages - src/mm/allocator.c:271
• allocate_mdt - src/mm/allocator.c:340
• allocator_init - src/mm/dymelor.c:41

[alessandropellegrini]

This was silently fixed in d868a3a.

Yet, the fix is partial as the code will flow across rootsim_error(). This is related to #12.

I consider anyhow this fixed, as soon as #12 is fixed, the requested behaviour will work.