Fix compilation warnings on clang-asan, clang-ubsan

[gaborcsardi]

There are only warnings now because of some C++20 features.

* checking whether package ‘otelsdk’ can be installed ... WARNING
Found the following significant warnings:
  /__w/otelsdk/otelsdk/check/otelsdk.Rcheck/00_pkg_src/otelsdk/src/cpp/sdk/src/common/env_variables.cc:84:3: warning: passing no argument for the '...' parameter of a variadic macro is a C++20 extension [-Wc++20-extensions]
...

From #53, #54.

[gaborcsardi]

Related: open-telemetry/opentelemetry-cpp#3121, specifically: open-telemetry/opentelemetry-cpp#3121 (comment)