[C++] Define and declare functions regardless of NDEBUG

[asfimport]

NDEBUG is not shipped in linker flags, so I got a linker error with release build on FixedSizeBinaryBuilder::UnsafeAppend(util::string_view value) call, since it makes a call to CheckValueSize.

This is somewhat a follow-up of ARROW-2313. I took the same path by removing NDEBUG ifdefs around CheckValueSize definition and declaration.

I applied the same fix to CheckUTF8Initialized as well after grepping the source code for "#ifndef NDEBUG" and figured out it has the same issue.

Reporter: Omer Ozarslan / @ozars
Assignee: Omer Ozarslan / @ozars

PRs and other links:

• GitHub Pull Request #5049
• GitHub Pull Request #5050

_{Note: This issue was originally created as ARROW-6190. Please see the migration documentation for further details.}

[asfimport]

Omer Ozarslan / @ozars:
Submitted PR on #5049.

[asfimport]

Antoine Pitrou / @pitrou:
Issue resolved by pull request 5049
#5049