ticket:10640:Merge r34877 to r34963 frm trunk.

git-svn-id: http://source.icu-project.org/repos/icu/icu@34964 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10483: Update #ifndef U_HIDE_XXX guards for 53m1

git-svn-id: http://source.icu-project.org/repos/icu/icu@34965 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10483: Further #ifndef U_HIDE_XXX adjustments from running hdrtst

git-svn-id: http://source.icu-project.org/repos/icu/icu@34966 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10483: Copy ICU4C trunk r34966 to tags/milestone-53-0-1

git-svn-id: http://source.icu-project.org/repos/icu/icu@34967 251d0590-4201-4cf1-90de-194747b24ca1