Bundle aarch64-none-elf-objdump 2.33 from Arm to simplify setup

Ubuntu 18.04's objdump is too old (2.30)

devkitA64's objdump is also too old (2.32) and doesn't support
--source-comment

README.md

@@ -38,7 +38,6 @@ Using a decompiler such as Hex-Rays or Ghidra is strongly recommended.
 
 You'll also need:
 
-* aarch64 binutils (Debian/Ubuntu package: `binutils-aarch64-linux-gnu`)
 * pip (for the diff script)
 * The original 1.5.0 `main` executable, converted to ELF format with [nx2elf](https://github.com/shuffle2/nx2elf).
     * Copy it to data/main.elf -- it is used for the diff script and other tools.

tools/diff_settings.py

@@ -5,4 +5,4 @@ def apply(config, args):
     config['baseimg'] = 'data/main.elf'
     config['myimg'] = 'build/uking'
     config['source_directories'] = ['src']
-    config['objdump_executable'] = 'aarch64-linux-gnu-objdump'
+    config['objdump_executable'] = 'tools/aarch64-none-elf-objdump'