Clang compiler warnings on qtbase

The flag 
-Wrange-loop-analysis (which seems to be on by default in clang) makes clang throw  a handful of warnings about loop variables passed by value even if they're declared as references.

Environment info:
MacOS 10.15.6

Apple clang version 12.0.0 (clang-1200.0.32.2)
Target: x86_64-apple-darwin19.6.0

Commands:

configure -developer-build -opensource -nomake examples -nomake tests -confirm-license -cmake
ninja
Solving this may yield increased performance as well.