Add 4068 to the list of warnings to suppress in VS.

We added pragmas to disable warnings from clang to i18n/decNum.c. They're
not recognized by Visual Studio. To suppress that warning, add 4068 
to the suppressed VC warning list. 

BUG=84851
TEST=Visual Stuido doesn't complain while compiling decNumc.
Review URL: https://chromiumcodereview.appspot.com/9355015

git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/icu46@122609 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
1 file changed