This reverts commit fd0e6053.

According to https://peter.eisentraut.org/blog/2014/12/01/ccache-and-clang-part-3
it's already fixed in new version of ccache

According to https://ccache.dev/manual/4.8.html#config_run_second_cpp


CCACHE_CPP2 are default to true for new version ccache

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Message-ID: <20231009165113.498-1-luoyonggang@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>