Additional Gdb compilation flag needed for clang16
Added -Wno-error=enum-constexpr-conversion for GDB compilation with clang16.
See the https://discourse.llvm.org/t/clang-16-notice-of-potentially-breaking-changes/65562 for more details of "potentially breaking changes in clang16"
Leaving in Draft status for the moment until we actually have/use a production version of clang16.