ICU-20119 63rc BRS, merge current unicode-icu master into cldr34a-integration branch

diff --cc icu4c/source/test/intltest/loctest.cpp
Simple merge

diff --cc icu4c/source/test/intltest/numbertest_api.cpp
Simple merge

diff --cc icu4c/source/test/intltest/numfmtst.cpp
Simple merge

diff --cc icu4c/source/test/intltest/tsmthred.cpp
Simple merge

diff --cc icu4c/source/test/testdata/numberformattestspecification.txt
Simple merge