Fix Windows clang compiler complaint

Fix Windows clang compiler complaint

https://codereview.chromium.org/1740533003 ( Initialize font fallback when creating DWrite font manager) seems to have broken the clang/win builds with:

..\..\third_party\skia\src\ports\SkFontMgr_win_dw.cpp(272,11) : error: field
'fLocaleName' will be initialized after field 'fFontFallback'
[-Werror,-Wreorder]
, fLocaleName(localeNameLength)
^
1 error generated.

I have also created skbug.com/5078 (Add Windows clang bot)

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1784533002

Review URL: https://codereview.chromium.org/1784533002