avro

[AVRO-4019] [C++] Turn on even more compiler warnings (#2966)

* [C++] Turn on -Wuseless-cast and -Wconversion

* Print versions of compiler/tools used in CI

* Fix another compiler warning

Also attempt to make build.sh continue

* Fix the last of the compiler warnings

* Update CodecTests.cc

* Update DataFileTests.cc

* Fix conversion warning on ARM64

* Hopefully make GCC 9.4 happy

* [C++] Address review comments