pch-reuse-split-pdb

• With MSVC and a separate program database (/Zi or /ZI), targets using PRECOMPILE_HEADERS_REUSE_FROM no longer lose debug information when the reused target changes but its precompiled header does not.

• With MSVC and a separate program database (/Zi or /ZI), targets using PRECOMPILE_HEADERS_REUSE_FROM now write the debug information of sources not compiled with the precompiled header, such as those with SKIP_PRECOMPILE_HEADERS, to their own compiler .pdb file, so it survives a rebuild of the precompiled header. See policy CMP0233.