Use correct linker flags for iOS release builds.

Use correct linker flags for iOS release builds.

iOS uses the same linker as Mac and thus should use the same linker flags
in Release mode (is_debug=false).

Fix the following error when linking base_unittest in Release mode:

FAILED: ../../third_party/llvm-build/Release+Asserts/bin/clang++ -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator9.0.sdk -stdlib=libc++ -mios-simulator-version-min=7.0 -Wl,-O1 -Wl,--gc-sections -Wl,--as-needed -o ./base_unittests.app/base_unittests -Wl,-filelist,./base_unittests.app/base_unittests.rsp  -framework UIKit -framework QuartzCore -framework OpenGLES -framework CoreFoundation -framework CoreGraphics -framework CoreText -framework Foundation
ld: unknown option: -O1

BUG=459705
Committed: https://crrev.com/5d2e00bce19e2fae5e1fa0419d78e92570026304
Cr-Commit-Position: refs/heads/master@{#342523}

[sdefresne, 2015-08-07 17:01:38]

sdefresne@chromium.org changed reviewers:
+ dpranke@chromium.org

[sdefresne, 2015-08-07 17:01:38]

Please take a look.

[sdefresne, 2015-08-07 17:03:10]

The CQ bit was checked by sdefresne@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-07 17:03:35]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1274633004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1274633004/1

[sdefresne, 2015-08-07 17:12:04]

sdefresne@chromium.org changed reviewers:
+ sherouk@google.com

[commit-bot: I haz the power, 2015-08-07 17:43:33]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-07 17:43:34]

Dry run: This issue passed the CQ dry run.

[sdefresne, 2015-08-07 18:48:11]

sdefresne@chromium.org changed reviewers:
+ brettw@chromium.org

[sdefresne, 2015-08-07 18:48:11]

+brettw

[Dirk Pranke, 2015-08-07 18:53:45]

lgtm

[brettw, 2015-08-07 20:20:40]

lgtm

[sdefresne, 2015-08-08 08:49:19]

The CQ bit was checked by sdefresne@chromium.org

[commit-bot: I haz the power, 2015-08-08 08:49:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1274633004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1274633004/1

[commit-bot: I haz the power, 2015-08-08 08:53:53]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-08 08:54:26]

Patchset 1 (id:??) landed as
https://crrev.com/5d2e00bce19e2fae5e1fa0419d78e92570026304
Cr-Commit-Position: refs/heads/master@{#342523}