GN: Fix flags writing for targets with unsupported PCHs

GN: Fix flags writing for targets with unsupported PCHs

This fixes an issue that led to empty compiler flags being written
in the unusual case of a target with a PCH in conjunction with a toolchain
that doesn't support PCHs.

BUG=649899
Committed: https://crrev.com/52de7c17a1f9e4b3a2ed57d41afd131c0f4f8e69
Cr-Commit-Position: refs/heads/master@{#424669}

[timn, 2016-10-11 16:31:02]

tim@rnc-ag.de changed reviewers:
+ brettw@chromium.org

[timn, 2016-10-11 16:31:03]

Previous attempt: https://codereview.chromium.org/2394163004/

[brettw, 2016-10-11 23:38:33]

lgtm

[timn, 2016-10-12 04:29:40]

The CQ bit was checked by tim@rnc-ag.de

[commit-bot: I haz the power, 2016-10-12 04:30:01]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-12 04:41:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-10-12 04:42:33]

Description was changed from

==========
GN: Fix flags writing for targets with unsupported PCHs

This fixes an issue that led to empty compiler flags being written
in the unusual case of a target with a PCH in conjunction with a toolchain
that doesn't support PCHs.

BUG=649899
==========

to

==========
GN: Fix flags writing for targets with unsupported PCHs

This fixes an issue that led to empty compiler flags being written
in the unusual case of a target with a PCH in conjunction with a toolchain
that doesn't support PCHs.

BUG=649899

Committed: https://crrev.com/52de7c17a1f9e4b3a2ed57d41afd131c0f4f8e69
Cr-Commit-Position: refs/heads/master@{#424669}
==========

[commit-bot: I haz the power, 2016-10-12 04:42:34]

Patchset 1 (id:??) landed as
https://crrev.com/52de7c17a1f9e4b3a2ed57d41afd131c0f4f8e69
Cr-Commit-Position: refs/heads/master@{#424669}