[clang] [CIR] Mark record members as data, pad, or empty in CIRGen (PR #215175)

[Adam Smith via cfe-commits]

================
@@ -380,6 +402,9 @@ CIRRecordLowering::accumulateBitFields(RecordDecl::field_iterator field,
     // used to determine if the ASTRecordLayout is treating these two bitfields
     // as contiguous. StartBitOffset is offset of the beginning of the Run.
     uint64_t startBitOffset, tail = 0;
+    // Where the current run's storage member sits in members, so that a named
+    // occupant joining the run can promote it to data.
+    size_t runStorageIdx = 0;
----------------
adams381 wrote:

I've renamed to `storageIdx`.

https://github.com/llvm/llvm-project/pull/215175