RFR: 8303621: BitMap::iterate should support lambdas and other function objects

[Kim Barrett]

Please review this enhancement of BitMap::iterate to support lambdas and other
function objects as the operation being applied to the set bit indices. Some
for-loops using BitMap::get_next_one_offset have been changed to use
BitMap::iterate with a lambda.

(One reason for changing the for-loops is that I'm considering a change to the
get_next_one_offset API, and reducing the number of direct uses will simplify
that.)

For convenience, the function can either return void (always iterate over the
whole range) or bool (stop iteration if returns false).  Iteration using
closure objects invoked via a do_bit member function are now implemented by
being wrapped in a lambda, so get the same convenience.  (Though, of course,
if the closure is derived from BitMapClosure then do_bit returns bool.)

The unit tests are written as "early" tests, not requiring an initialized VM.
They also avoid any C heap allocation (even though C heap allocation has very
early support). This is done to minimize the requirements for running the
tests, since BitMap is used in a lot of places. This attempts to run these
tests before uses. (Yes, I know about JDK-8257226; maybe that will be fixed
someday.) (Some existing BitMap gtests should be modified to do similarly; see
JDK-8303636.)

Testing:
mach5 tier1-7

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Commit messages:
 - use iterate with lambda
 - bitmap iteration supports lambda

Changes: https://git.openjdk.org/jdk/pull/12876/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12876&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303621
  Stats: 302 lines in 5 files changed: 260 ins; 8 del; 34 mod
  Patch: https://git.openjdk.org/jdk/pull/12876.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12876/head:pull/12876

PR: https://git.openjdk.org/jdk/pull/12876