HHH-8401 : Support fractional seconds on MySQL 5.7

(cherry picked from commit fe94cda1d1a2ede18b5a577e3ac80db85a806ef3)

Conflicts:
	hibernate-core/src/main/java/org/hibernate/dialect/function/NoArgSQLFunction.java
HHH-8401 : Support fractional seconds on MySQL 5.7 (tweak test cases for 4.2)