Roll GN from "UNKNOWN" to 1413 (4cf8d15..e134e49).

This roll is done manually based loosely on the script from scottmg@
in https://crrev.com/c/1120646. We need to land a proper script
and automate this further. The "UNKNOWN" version we were running before
was actually built @ 4cf8d15, but we didn't have the --version
flag working yet.

  $ git log 4cf8d15..e134e49 --date=short --no-merges --format='%h %ad %s'
  e134e493 2018-08-13 Support specifying target and host platform in gen.py
  dd6a3831 2018-08-13 Switch to libc++ on Linux
  c218b836 2018-07-02 Don't use -- in exec_script
  27ef6b4e 2018-08-13 Fix gn_unittests
  f8f395ac 2018-08-10 Remove sarcastic error message.
  f9dbfd12 2018-08-10 Avoid trailing slashes for directory in compilation database
  c0744edf 2018-08-04 Add string_replace builtin function
  09171294 2018-07-31 [output_conversion] Add output_conversion options
  c2717deb 2018-08-02 [compdb] Properly escape for JSON
  f4facf42 2018-08-04 Don't allow ./ before target name.
  499868c6 2018-07-18 port gn to aix
  387e3ab4 2018-07-23 Add an OWNERS file.
  11e09914 2018-07-31 [docs] Updating documentation for compdb
  e2a2940a 2018-07-31 [target] Propagate configs across toolchains when specified
  d2d7ecb2 2018-07-30 Default to "ar" instead of "llvm-ar"
  9ae36b8b 2018-06-13 Update AUTHORS to reflect Chromium-tree contributions
  9a9ed6df 2018-07-26 Move all docs to toplevel docs/ folder.
  cad6b537 2018-07-23 Add notes about the CLA and gn-dev@ to the README.
  5d9a4e9a 2018-07-20 Make ICF an option in gen.py
  d7111cb6 2018-07-16 Enable identical code folding link option
  a6c2a5d5 2018-07-15 Use -ffunction-sections and -fdata-sections
  796ed47b 2018-07-16 Add reference.md
  63b72701 2018-07-15 Make LTO an option in gen.py
  d9bca564 2018-07-13 Fixes for --out-path and --no-sysroot
  0e4f3935 2018-07-13 Add options necessary for Chromium's bootstrap.py to forward to gen.py
  6ef28560 2018-07-13 Correct grammar in current_{cpu,os} docs
  8ce4e49a 2018-07-02 [gn] Add --export-compile-commands switch to gen
  f0b4405f 2018-07-09 Don't pass -flto.
  9911c782 2018-07-03 [command_args] Properly set file and line in dict
  39687ba9 2018-07-03 [command_args] Strip the preceding whitespace in comments if not padding
  fdc7a748 2018-06-29 Improve --version per discussion
  9cd5057b 2018-06-29 [recipes] Add --tags to git fetch command
  3ddcf64a 2018-06-29 Make gn --version work

To-be-Reviewed: brettw@chromium.org

Change-Id: I5ef29d91c8e7d2b8525105b868e876a6bab63d8a
3 files changed