Add missing unicode_width dependency to compiler-builtins-dummy

This fixes some Android and macOS builds using the the
extra-targets path on Debian stable.

Author: TheBlueMatt

deterministic-build-wrappers/compiler-builtins-dummy/Cargo.toml

@@ -9,3 +9,4 @@ gimli = "=0.25.0"
 object = "=0.26.2"
 addr2line = "=0.16.0"
 miniz_oxide = "=0.4.4"
+unicode_width = "=0.2.1"