Fix --filetype=iasm non-pc-rel fixup offsets (double counted).

src/IceAssembler.cpp

Index: src/IceAssembler.cpp
diff --git a/src/IceAssembler.cpp b/src/IceAssembler.cpp
index 48db0363916ca2e9b874d9ab78a7c20a97fcb419..5c1760b46313aa6c9b26af6e6406ec0948f7ee81 100644
--- a/src/IceAssembler.cpp
+++ b/src/IceAssembler.cpp
@@ -132,6 +132,10 @@ void Assembler::emitIASBytes(GlobalContext *Ctx) const {
       Str << "\n";
     }
     Str << "\t.long ";
+    // For PCRel fixups, we write the pc-offset from a symbol into the Buffer
+    // (e.g., -4), but we don't represent that in the fixup's offset.
+    // Otherwise the fixup holds the true offset, and so does the Buffer.
+    // Just load the offset from the buffer.
     NextFixup->emit(Ctx, Buffer.load<RelocOffsetT>(NextFixupLoc));
     if (fixupIsPCRel(NextFixup->kind()))
       Str << " - .";