Check fallthrough in mount.h for Mac

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk/usr/include/os/base.h:128:23: error: missing ')' after 'do'
                      ^~~~~~~~~~~
external/f2fs-tools/include/f2fs_fs.h:81:24: note: expanded from macro 'fallthrough'
                    ~~ ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk/usr/include/os/base.h:128:22: note: to match this '('

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2 files changed