[foreign-memaccess+abi] RFR: 8293400: Modify static constructors in MemorySegment [v2]

[Per Minborg]

On Tue, 13 Sep 2022 11:58:45 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Simplify creatons of MemorySegments in tests
>
> test/jdk/java/foreign/TestByteBuffer.java line 764:
> 
>> 762:     public static Object[][] segments() throws Throwable {
>> 763:         return new Object[][] {
>> 764:                 { (Supplier<MemorySegment>) () -> MemorySession.openImplicit().allocate(16) },
> 
> This could use `allocateNative`

I intentionally left that as-is to adhere to the `openConfined()` on the following line.

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PR: https://git.openjdk.org/panama-foreign/pull/718