Fix assertion failures under DISABLE_NDEBUG

This CL updates lexical contexts when moving fields between struct
declarations, a key part of the small structure fix, so that clang stops
complaining about that inconsistency, and also fixes a minor assertion
failure related to getAttrs() on declarations that have no attributes.

Bug: 37099228
Test: slang/lit-tests, cts, RsTest (without DISABLE_NDEBUG) on Angler
Test: mm within framework/rs with FORCE_BUILD_LLVM_DISABLE_NDEBUG=true
Change-Id: Ie79c7715a3262214c3a4702cd1cc4cdc2680b954
1 file changed