Add GN files that need exec_script to list for win64 clang-cl

Add GN files that need exec_script to list for win64 clang-cl

TBR=kjellander@chromium.org
BUG=libyuv:649
TEST=call gn gen out\Release "--args=is_debug=false is_clang=true"

Committed: https://chromium.googlesource.com/libyuv/libyuv/+/a7166c337514e37646de97f4aad81254358cc92c

[fbarchard1, 2016-10-12 19:38:05]

fbarchard@google.com changed reviewers:
+ kjellander@chromium.org

[fbarchard1, 2016-10-12 19:38:05]

this allows GN to generate ninja files for win64 clang-cl

Was
call gn gen out\Release "--args=is_debug=false is_clang=true"
ERROR at //build/config/win/BUILD.gn:88:9: Disallowed exec_script call.
    if (exec_script("//build/win/use_ansi_codes.py", [], "trim string") ==
        ^-------------------------------------------------------------
The use of exec_script use is restricted in this build. exec_script
is discouraged because it can slow down the GN run and is easily
abused.

Generally nontrivial work should be done as build steps rather than
when GN is run. For example, if you need to compute a nontrivial
preprocessor define, it will be better to have an action target
generate a header containing the define rather than blocking the GN
run to compute the value.

The allowed callers of exec_script is maintained in the "//.gn" file
if you need to modify the whitelist.
See //build/config/BUILDCONFIG.gn:483:5: which caused the file to be included.
    "//build/config/win:lean_and_mean",
    ^---------------------------------

Now
call gn gen out\Release "--args=is_debug=false is_clang=true"
Done. Made 42 targets from 42 files in 527ms

[fbarchard1, 2016-10-12 19:45:59]

Description was changed from

==========
Add GN files that need exec_script to list for win64 clang-cl

BUG=libyuv:649
TEST=call gn gen out\Release "--args=is_debug=false is_clang=true"
==========

to

==========
Add GN files that need exec_script to list for win64 clang-cl

TBR=kjellander@chromium.org
BUG=libyuv:649
TEST=call gn gen out\Release "--args=is_debug=false is_clang=true"
==========

[fbarchard1, 2016-10-12 19:46:27]

Description was changed from

==========
Add GN files that need exec_script to list for win64 clang-cl

TBR=kjellander@chromium.org
BUG=libyuv:649
TEST=call gn gen out\Release "--args=is_debug=false is_clang=true"
==========

to

==========
Add GN files that need exec_script to list for win64 clang-cl

TBR=kjellander@chromium.org
BUG=libyuv:649
TEST=call gn gen out\Release "--args=is_debug=false is_clang=true"

Committed:
https://chromium.googlesource.com/libyuv/libyuv/+/a7166c337514e37646de97f4aad...
==========

[fbarchard1, 2016-10-12 19:46:28]

Committed patchset #2 (id:20001) manually as
a7166c337514e37646de97f4aad81254358cc92c (presubmit successful).

[kjellander_chromium, 2016-10-12 20:19:09]

lgtm