[NQP Bump] Brings 18 commits

NQP bump brought: Raku/nqp@2018.12-63-gbabdab44f...2018.12-81-g6e75b0476
6e75b0476 Don't use `note` in the cursor role
5ce0d49f4 [jvm] Implement utf16be support
6e9984bbc Test the utf16be encoding
fcab35985 [js] Implement the utf16be encoding
d4efbc349 [js] Move misplaced codecs helper function
1b1204066 [js] Remove hard coded list of special casing codecs
0ce23b3fe [js] Move special encoding checking from ifs into methods
78a499242 [js] Fix problem with attributerefs in async mode
6ace18e55 [js] Fix ignored side effect when building a chunk
95d5bec3c Test boolification of boxed str nulls
d3ca93baf [js] Remove TODO placeholder for hints
d06b7eae5 [js] Handle nqp::null_s in string unboxing boolification modes
f1c04c252 [js] Fake only positive pids
94cba478a [js] Fix bug in nqp::radix_I
962a4071d [js] Fix test description
0cf69e49f [js] When faking a pid in the browser make it a positive integer
413b71b9a [js] Sprinkle async/await on unicode property checks
af276adb9 [js] Add missing p6$ prefix to method call

tools/build/NQP_REVISION

@@ -1 +1 @@
-2018.12-63-gbabdab44f
+2018.12-81-g6e75b0476