linux OOM must set errno to ENOMEM

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on June 14, 2013 16:14:05_

from man malloc:

```
The UNIX 98 standard requires malloc(), calloc(), and realloc() to set
errno to ENOMEM upon failure. Glibc assumes that this is done (and the
glibc versions of these routines do this); if you use a private malloc
implementation that does not set errno, then certain library routines
may fail without having a reason in errno.
```

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=1273_