tools/eclipse/project.py: Restore Java 8 compatibility
tools/eclipse/project.py: Restore Java 8 compatibility

In Ie341cd4dfe Eclipse JRE value "JavaSE-1.8" was inadvertently replaced
with "JavaSE-9". Restore JRE to the previous value.

Change-Id: I7e4860d8c611452399beaf972b6810f5b7ba755e

GerritCodeReview/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,WANdisco/gerrit