[clang] [clang][bytecode] Implement arithmetic, bitwise and compound assignment operator (PR #108949)

[Rainer Orth via cfe-commits]

rorth wrote:

Just for the record: in a 2-stage `sparc64-unknown-linux-gnu` build, the failures occur, too.  So nothing Solaris-specific in here.  Maybe endianess?

https://github.com/llvm/llvm-project/pull/108949