[clang][utils] Modify make-ast-dump-check.sh to generate AST serialization dump tests

[clang][utils] Modify make-ast-dump-check.sh to generate AST serialization dump tests

An AST serialization dump test is a test which compares the output of -ast-dump
on the source and of -ast-dump-all on a PCH generated from the source. Modulo
a few differences the outputs should match.

This patch to make-ast-dump-check.sh enables automatically generating
these tests.

Differential Revision: https://reviews.llvm.org/D81786

Reviewed By: aaron.ballman, lebedev.ri