This PR fixes
ICU-21043 Erroneous date display in indian calendar of all dates prior to 0001-01-01.
ICU-21044 Hebrew Calendar calculation is incorrect when the year < 1
ICU-21045 Erroneous date display in islamic and islamic-rgsa calendars of all dates prior to 0622-07-18.
ICU-21046 Erroneous date display in islamic-umalqura calendar of all dates prior to -195366-07-23.
The problem in the indiancal.cpp is
* ICU-21043 the gregorian/julain convesion is wrong. Swith to use
i18n/gregoimp.h fix the problem.
The problem in the hebrwcal.cpp is
* ICU-21044 Use ClockMath::floorDivid to replace x / y for x maybe < 0
also need to fix incorrect value in test file
The problem in the islamcal.cpp:
* ICU-21045: The math of % negative number for year and month is wrong.
* ICU-21046: Not use int64_t methods and caused int32_t overflow while the year is a
huge negative number. Cast to int64_t to force using the int64_t version
for the math fix the problem.
Also add tests to exhaust test 8000 years for all calendar. In quick
mode, only test 2.5 years.
Switch to 0-based month. fix TZ for test.
35dfdf1d02