Fix clang-tidy cppcoreguidelines-pro-type-const-cast warning

Fix clang-tidy cppcoreguidelines-pro-type-const-cast warning

clang-tidy reports:
cppcoreguidelines-pro-type-const-cast; do not use const_cast

The const_cast adds a const qualifier so this warning seems a bit
strict. Regardless, we can dodge the whole question by passing the
exclusion_list as `const char * const *`, which is closer to the
original intention of the API anyhow.

For more information on the safety of these types of casts, see:
https://isocpp.org/wiki/faq/const-correctness#constptrptr-conversion

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ia3129b7d1ed4e450f3f2d63920d2fd67c66a6d73