Add a 'unique id' for TagDecls for type uniquing.

libclang's getFullyQualifiedName API can miss default template arguments
and sometimes does not fully qualify template parameters as well. So for
type uniquing, use the API used by LLVM for TBAA : mangleCXXRTTIName.

Test: tests/test.py, all tests pass.

Bug: 69568963

Change-Id: Ibc97f5d3b0a1cb0eeed5f5df3e9c373bcb9573b4
126 files changed