UBUNTU: [Packaging] depend on clang/libclang-15 for Rust

Make sure to use clang/libclang-15 for Rust, since the default
clang/libclang-16 has some build incompatibilities with gcc-13,
triggering the following error:

  BINDGEN rust/bindings/bindings_generated.rs
  thread 'main' panicked at '"ftrace_branch_data_union_(anonymous_at__/_/include/linux/compiler_types_h_146_2)" is not a valid Ident',
  +/build/rust-bindgen-0.56-DgAMvF/rust-bindgen-0.56-0.56.0/debian/vendor/proc-macro2-1.0.24/src/fallback.rs:693:9

Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

debian.master/control.stub.in

@@ -39,6 +39,8 @@ Build-Depends:
  curl <!stage1>,
  zstd <!stage1>,
  pahole [amd64 arm64 armhf ppc64el s390x riscv64] | dwarves (>= 1.21) [amd64 arm64 armhf ppc64el s390x riscv64] <!stage1>,
+ clang-15 [amd64],
+ libclang-15 [amd64],
  rustc-1.68 [amd64],
  rust-1.68-src [amd64],
  rustfmt-1.68 [amd64],

debian/rules.d/0-common-vars.mk

@@ -239,7 +239,7 @@ kmake = make ARCH=$(build_arch) \
 	HOSTCC=$(HOSTCC) \
 	CC=$(CROSS_COMPILE)$(gcc) \
 	RUSTC=rustc-1.68 HOSTRUSTC=rustc-1.68 BINDGEN=bindgen-0.56 RUSTFMT=/usr/lib/rust-1.68/bin/rustfmt RUST_LIB_SRC=/usr/src/rustc-1.68.2/library \
-	CLANG_PATH=clang-14 LIBCLANG_PATH=/usr/lib/llvm-14/lib \
+	CLANG_PATH=clang-15 LIBCLANG_PATH=/usr/lib/llvm-15/lib \
 	KERNELVERSION=$(abi_release)-$(target_flavour) \
 	CONFIG_DEBUG_SECTION_MISMATCH=y \
 	KBUILD_BUILD_VERSION="$(uploadnum)" \