Only enable shared libc++ for ASan, MSan and TSan builds.

Only enable shared libc++ for ASan, MSan and TSan builds.

The UBSan runtime, which is also used by CFI, does not override the
allocator functions, so there is no need to link libc++ dynamically
if the UBSan runtime is being linked.

The goal is to ensure that CFI coverage when building with use_cfi_diag
is the same as when building without, and to avoid potential false
positives in the standard library when building with use_cfi_icall.

BUG=701919
R=thakis@chromium.org, thomasanderson@chromium.org

Committed: 3d2d34dde457f07ca410d1c06f4f3b9063c28643

[Tom Anderson, 2017-07-12 01:33:55]

On 2017/07/12 01:27:35, pcc1 wrote:

lgtm; when you roll in Chromium, please also update these references:
https://cs.chromium.org/search/?q=%22It+is+currently+copied+from%22&sq=packag...

[Nico, 2017-07-12 01:36:40]

lgtm

[pcc1, 2017-07-12 01:41:26]

Description was changed from

==========
Only enable shared libc++ for ASan, MSan and TSan builds.

The UBSan runtime, which is also used by CFI, does not override the
allocator functions, so there is no need to link libc++ dynamically
if the UBSan runtime is being linked.

The goal is to ensure that CFI coverage when building with use_cfi_diag
is the same as when building without, and to avoid potential false
positives in the standard library when building with use_cfi_icall.

BUG=701919
R=thakis@chromium.org,thomasanderson@chromium.org
==========

to

==========
Only enable shared libc++ for ASan, MSan and TSan builds.

The UBSan runtime, which is also used by CFI, does not override the
allocator functions, so there is no need to link libc++ dynamically
if the UBSan runtime is being linked.

The goal is to ensure that CFI coverage when building with use_cfi_diag
is the same as when building without, and to avoid potential false
positives in the standard library when building with use_cfi_icall.

BUG=701919
R=thakis@chromium.org, thomasanderson@chromium.org

Committed: 3d2d34dde457f07ca410d1c06f4f3b9063c28643
==========

[pcc1, 2017-07-12 01:41:27]

Committed patchset #1 (id:1) manually as
3d2d34dde457f07ca410d1c06f4f3b9063c28643 (presubmit successful).