RFR for CODETOOLS-7902293 and 7902317 jcheck extension broken in recent builds of hg

[Tim Bell]

Hello

Two changes in recent builds of hg broke jcheck:

1) CODETOOLS-7902292: util.Abort() was moved/copied from util to error 
in hg 1.3 and was removed from util in 4.6.  This is the same fix used 
on trees.py back in July [1].

2) CODETOOLS-7902317: date-related utils moved from util to 
utils/dateutil in early 2018 (hg 4.7).

http://cr.openjdk.java.net/~tbell/CODETOOLS-7902293-7902317/webrev/

Tested with hg versions 0.9.5, 2.9, 3.2.3, 4.7

Thanks in advance.  I will also need a sponsor to push the change for me.

Tim

[1] Ref lines 140 ... 146: 
http://hg.openjdk.java.net/code-tools/trees/comparison/592eba45b774/trees.py