Filter out a few more files from NaCl build of base/

Filter out a few more files from NaCl build of base/

Some files like important_file_writer, and stack_trace will
fail to link if they are ever linked in, because what they
depend on has already been filtered out (file_util,
file_util_posix and stack_trace_posix).

Others just don't seem necessary (parts of base/process/).

This helps a little w/ an upcoming pnacl LLVM 3.6 merge,
but doesn't fully solve a linking problem. Otherwise
it's fewer files to build w/ a NaCl compiler.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4026

Committed: https://crrev.com/8227220d20b31c22740a73e8466e65157950b020
Cr-Commit-Position: refs/heads/master@{#312852}

[jvoung (off chromium), 2015-01-23 03:51:38]

jvoung@chromium.org changed reviewers:
+ mark@chromium.org, mseaborn@chromium.org

[jvoung (off chromium), 2015-01-23 03:51:57]

jvoung@chromium.org changed reviewers:
+ bbudge@chromium.org

[Mark Seaborn, 2015-01-23 04:08:29]

LGTM

[Mark Mentovai, 2015-01-23 04:38:29]

LGTM

[bbudge, 2015-01-23 13:13:01]

lgtm

[jvoung (off chromium), 2015-01-23 15:46:14]

The CQ bit was checked by jvoung@chromium.org

[commit-bot: I haz the power, 2015-01-23 15:47:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/870863003/20001

[commit-bot: I haz the power, 2015-01-23 15:51:37]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-23 15:52:41]

Patchset 2 (id:??) landed as
https://crrev.com/8227220d20b31c22740a73e8466e65157950b020
Cr-Commit-Position: refs/heads/master@{#312852}