[analyzer][MallocChecker] PR46253: Correctly recognize standard realloc

https://bugs.llvm.org/show_bug.cgi?id=46253

This is an obvious hack because realloc isn't any more affected than other
functions modeled by MallocChecker (or any user of CallDescription really),
but the nice solution will take some time to implement.

Differential Revision: https://reviews.llvm.org/D81745