RFR: JDK-8293711: Factor out size parsing functions from arguments.cpp [v3]

[Thomas Stuefe]

> Arguments.cpp has several size parsing functions which would be useful in other areas of the hotspot, e.g. in NMT.
> 
> It would be nice to have them factored out into utilities, to reuse the code and to unify memory size handling. Gtests would be good too.
> 
> To simplify reviews, I split the patch into two commits.
> 
> The first commit (https://github.com/openjdk/jdk/pull/10252/commits/700e77e8d1469a2fc3d6611072c4b07aa34ab8e6) contains the unchanged code move without functional changes.
> 
> The second commit (https://github.com/openjdk/jdk/pull/10252/commits/76b4f6f30cc316fd966da60ff6601f54eeb394bf) contains the functional changes I did, as well as the new gtest.

Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:

  Feedback stefank+dholmes

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/10252/files
  - new: https://git.openjdk.org/jdk/pull/10252/files/a5e6b6f1..339fab1f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10252&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10252&range=01-02

  Stats: 9 lines in 5 files changed: 3 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/10252.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10252/head:pull/10252

PR: https://git.openjdk.org/jdk/pull/10252