Make wrappers guess type of NULL as nullptr_t.

When the wrappers encounter NULL in a header file, specifically in the case
of "#define something NULL", it now treated as a value of type nullptr_t,
similar to nullptr itself.  This ensures that NULL will not be wrapped as
int, even if it is defined to be 0.
1 job for wrap-null-as-nullptr_t
Status Job ID Name Coverage
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