Update wasm-sysroot-usr.diff to fix #1029010
Update the wasm-sysroot-usr.diff patch to restore functionality that was accidentally dropped when the patch was forward-ported from 14 to 15. This resolves an issue in which clang++ builds would fail if libc++-15-dev was installed alongside libc++-15-dev-wasm32.
This issue was rightfully caught in the autopkgtests, and has prevented the package from migrating to testing, something that should hopefully be resolved now.
Update: tested as a cherry-pick over 1:15.0.7-1 and works as intended.
Edited by Faidon Liambotis