Undefine CHECK while including slicer headers.

The headers of slicer define and export a CHECK macro. This causes
problems since it conflicts with the CHECK macro exported by libbase.
We temporarily undefine the libbase CHECK macro while including the
slicer headers so we don't run into any problems.

Bug: 65422458
Test: mma -j40
Change-Id: I0da54f5710927bad273d25882f63df927022ceae