RFR: 8316433: net.dll should delay load winhttp.dll [v2]

[Daniel Jeliński]

> WinHTTP functions are only used when an application:
> - uses DefaultProxySelector to resolve proxies, and
> - is run with -Djava.net.useSystemProxies=true
> 
> In all other cases, loading winhttp.dll is a waste of resources.
> 
> Verified that:
> - existing tier1 and tier2 tests still pass
> - the same system proxies are returned with and without this patch
> - WinHTTP is not loaded unless DefaultProxySelector is used

Daniel Jeliński has updated the pull request incrementally with one additional commit since the last revision:

  Revert test changes

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15793/files
  - new: https://git.openjdk.org/jdk/pull/15793/files/16e43b79..6a382ca3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15793&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15793&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/15793.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15793/head:pull/15793

PR: https://git.openjdk.org/jdk/pull/15793