MariaDB 10.8 macOS build flags

MariaDB 10.8 macOS CMake flags: -DCMAKE_BUILD_TYPE=Debug -DCMAKE_C_FLAGS="-isystem /usr/local/include" -DCMAKE_CXX_FLAGS="-isystem /usr/local/include" -DPLUGIN_MROONGA=NO -DPLUGIN_CONNECT=NO

The -isystem one is required to find Homebrew-installed Snappy, as /usr/local/include is not in the default XCode include search path since their move to sysroots.

The plugin disables workaround compilation errors. More unneeded stuff could be disabled for faster builds.