[C++] Consider making default_memory_pool() the default for builder classes

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To make this work, we would also need to make MemoryPool* the last argument in some of the builder constructors. @xhochy what do you think?

see also ARROW-1210

Reporter: Wes McKinney / @wesm
Assignee: Wes McKinney / @wesm

_{Note: This issue was originally created as ARROW-1211. Please see the migration documentation for further details.}

[asfimport]

Uwe Korn / @xhochy:
@wesm I'm infavor of that but would also like to have a define, e.g NO_ARROW_DEFAULT_MEMORY_POOL that I could use as a Arrow consumer to ensure that I'm not using the default memory pool but actually pass the memory pools along.

[asfimport]

Wes McKinney / @wesm:
PR: #923

[asfimport]

Wes McKinney / @wesm:
Resolved by ee928d2