Cover ThaiBuddhistDate with tests.

Cover ThaiBuddhistDate.minus(TemporalAmount) with unit test.

Bug: 182165762
Test: atest libcore.java.time.chrono.ThaiBuddhistDateTest

(cherry picked from commit 4efeaa64a196fd7a5c62efae3236108a8ce04673)

Change-Id: Ie15827e99aa3e0bccc0456f4ead4fbcefb3463f4
Merged-In: Ie15827e99aa3e0bccc0456f4ead4fbcefb3463f4
1 file changed