[nanodbc] Allow specifing the ODBC version for nanodbc

[AnthonyCalandra]

This patch adds the option to specify an ODBC version directly to the nanodbc library, which up to this point has been looking for ODBC versions itself (see here). It only passes in the NANODBC_ODBC_VERSION option to nanodbc's cmake script if this flag has been set by the user.

• What does your PR fix?

  See the following comment on what this PR is fixing: SQL_OV_ODBC3_80 issue on Ubuntu 16.04 with unixODBC 2.3.1 nanodbc/nanodbc#114 (comment)
  I experienced this issue on a CentOS box with unixODBC 2.3.1. In summary: unixODBC 2.3.1 reports an incorrect ODBC version which nanodbc picks up, but should be overridden with the version passed in through NANODBC_ODBC_VERSION.

• Which triplets are supported/not supported? Have you updated the CI baseline?

  Not sure I need to update the baseline file; please let me know if I do.

• Does your PR follow the maintainer guide?

  Yes

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

  Yes

[ghost]

All CLA requirements met.

[AnthonyCalandra]

I didn't pass this in directly as an option because nanodbc's cmake file only checks to see if NANODBC_ODBC_VERSION is defined -- unlike an option which can be either ON/OFF. See: https://github.com/nanodbc/nanodbc/blob/master/CMakeLists.txt#L78

[dg0yt]

Actually the value of NANODBC_ODBC_VERSION is passed on to the compilation:

https://github.com/nanodbc/nanodbc/blob/cbc4ec2418a9feec559e06ea5dc0a632f305d5d1/CMakeLists.txt#L81-L82

And how is it specified for building port nanodbc? Would I need to modify the triplet?

[AnthonyCalandra]

I think my original comment wasn't clear enough. Yes, it is passed to the compilation, but I'm talking about embedding the option directly, i.e.

vcpkg_configure_cmake(
    SOURCE_PATH ${SOURCE_PATH}
    PREFER_NINJA
    OPTIONS
        -DNANODBC_DISABLE_EXAMPLES=ON
        -DNANODBC_DISABLE_TESTS=ON
        -DNANODBC_ENABLE_UNICODE=OFF
        -DNANODBC_ODBC_VERSION=${NANODBC_ODBC_VERSION}
)

I made this comment to make it clear I intentionally didn't do it this way.

As for your second question, that's correct, you could add a line to the triplet file, and that's what I did on my machine (another work-around without adding this patch would be setting the flag as part of VCPKG_CXX_FLAGS but this patch is more appropriate IMO).

[JackBoosY]

Depends on #17983.