Moved the whole SMT API to a single file. NFC.

There is no advantage in having them in separate files, I doubt some will ever use them separately.

This also makes it easier to move the API to LLVM.

Differential Revision: https://reviews.llvm.org/D54977

llvm-svn: 353372
GitOrigin-RevId: 5f16ad9a1be845fef99155278bc5743e357664cd
4 files changed