[foreign-abi] RFR: 8253360: LibraryLookup javadoc should be clearer about how to create restricted segments [v2]

[Maurizio Cimadamore]

> This patch adds a better description of how clients are supposed to derive segments from a lookup symbol, by stating
> the need of keeping the symbol alive via segment attachment.
> I also fixed a missing type parameter javadoc in the VaList API.

Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:

  Repeat javadoc guidance on LibraryLookup.Symbol::address()

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/345/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/345/files/025b7cd9..1a443c73

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=345&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=345&range=00-01

  Stats: 5 lines in 1 file changed: 2 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/345.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/345/head:pull/345

PR: https://git.openjdk.java.net/panama-foreign/pull/345