Fix x64 Windows builds break.

[secure-sw-dev-bot]

This issue was copied from checkedc/checkedc-clang#917

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After merging the work on the Checked C converter, two failures appeared only on automated debug x64 Windows build.

One error was that the compiler was trying to create an object file that had too many sections. This adds the /bigobj flag for some files, which allows a newer object file format to be used. The other error was that an include file was missing in the Checked C converter tool.

With these changes, the automated testing passes again for the debug x64 Windows build.