[MIPS] Modify NaClFindAddressSpaceRandomized to find appropriate address
[MIPS] Modify NaClFindAddressSpaceRandomized to find appropriate address

mmap can return differently aligned value depending on the input arguments
it is given. Thus, MAP_SHARED is passed to mmap as it can require more rigid
alignment on MIPS. In addition to that, for the same reason the mask we
apply to the randomized address value is 2 x system page size.

This change will fix the following failures on Mips hardware:

- run_gio_shm_unbounded_test,
- run_nacl_desc_io_alloc_ctor_test.

NOTRY=true
However, we have run a try job manually, and it passed fine, except for
the nacl-lucid64_validator_opt that is broken.

BUG= the aforementioned tests
TEST= run the failing tests

Review URL: https://chromiumcodereview.appspot.com/18322006

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@11820 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client