ac: use ResetAllOptionOccurrences instead of ResetCommandLineParser

Fixes -amdgpu-atomic-optimizations=true option.

From CommandLine.h:

/// Reset all command line options to a state that looks as if they have
/// never appeared on the command line.  This is useful for being able to parse
/// a command line multiple times (especially useful for writing tests).
void ResetAllOptionOccurrences();

/// Reset the command line parser back to its initial state.  This
/// removes
/// all options, categories, and subcommands and returns the parser to a state
/// where no options are supported.
void ResetCommandLineParser();