clang/win: For 64-bit builds, enable warnings-as-errors and stop falling back to CL.
clang/win: For 64-bit builds, enable warnings-as-errors and stop falling back to CL.

Clang can now build all of chrome's translation units in 64-bit.  Remove
/fallback so that the bot will turn red if this regresses.

Also turn on warnings-as-errors, so that warnings also turn the build red
(instead of just causing a fallback as before).

Also remove a superfluous 'RuntimeTypeInfo': 'false': This is already the
default for non-clang builds too.  (And for the few places where we do need
RTTI -- icu -- clang has been able to emit it for months now.)

BUG=82385
R=hans@chromium.org

Review URL: https://codereview.chromium.org/921633004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#316141}

hgl888/chromium-crosswalk,fujunwei/chromium-crosswalk,axinging/chromium-crosswalk,ltilve/chromium,ltilve/chromium,Fireblend/chromium-crosswalk,Chilledheart/chromium,Chilledheart/chromium,chuan9/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,hgl888/chromium-crosswalk,chuan9/chromium-crosswalk,axinging/chromium-crosswalk,Just-D/chromium-1,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Just-D/chromium-1,Fireblend/chromium-crosswalk,Just-D/chromium-1,axinging/chromium-crosswalk,axinging/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,fujunwei/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,fujunwei/chromium-crosswalk,chuan9/chromium-crosswalk,chuan9/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,hgl888/chromium-crosswalk,Fireblend/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,hgl888/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Fireblend/chromium-crosswalk,chuan9/chromium-crosswalk,chuan9/chromium-crosswalk,Fireblend/chromium-crosswalk,ltilve/chromium,TheTypoMaster/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Just-D/chromium-1,Chilledheart/chromium,PeterWangIntel/chromium-crosswalk,Just-D/chromium-1,Chilledheart/chromium,Chilledheart/chromium,hgl888/chromium-crosswalk,fujunwei/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Fireblend/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,ltilve/chromium,PeterWangIntel/chromium-crosswalk,Just-D/chromium-1,fujunwei/chromium-crosswalk,Fireblend/chromium-crosswalk,hgl888/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,ltilve/chromium,TheTypoMaster/chromium-crosswalk,Fireblend/chromium-crosswalk,Just-D/chromium-1,ltilve/chromium,chuan9/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,fujunwei/chromium-crosswalk,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,hgl888/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,axinging/chromium-crosswalk,ltilve/chromium,chuan9/chromium-crosswalk,fujunwei/chromium-crosswalk,axinging/chromium-crosswalk,fujunwei/chromium-crosswalk,Pluto-tv/chromium-crosswalk,ltilve/chromium,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Chilledheart/chromium,PeterWangIntel/chromium-crosswalk,Pluto-tv/chromium-crosswalk,fujunwei/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Just-D/chromium-1,Pluto-tv/chromium-crosswalk,chuan9/chromium-crosswalk,axinging/chromium-crosswalk,Just-D/chromium-1,hgl888/chromium-crosswalk,Fireblend/chromium-crosswalk,ltilve/chromium,axinging/chromium-crosswalk,Chilledheart/chromium,hgl888/chromium-crosswalk