downloads: LLVM 16.0.3 -> 17.0.6 (macOS)

This was blocked on libffi 3.3 -> 3.4, as 3.3 had compile errors
on macOS using latest LLVM. Now that we upgraded to 3.4, things appear
to "just work."

Author: indygreg

pythonbuild/downloads.py

@@ -182,16 +182,16 @@
         "version": "17.0.6+20240107",
     },
     "llvm-aarch64-macos": {
-        "url": "https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20230506/llvm-16.0.3+20230506-aarch64-apple-darwin.tar.zst",
-        "size": 116375025,
-        "sha256": "f8353cbeadc4be9d83a2b0ae1dc48efe80a4700dac5bd6bdc8058b9144336479",
-        "version": "16.0.3+20230506",
+        "url": "https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20240107/llvm-17.0.6+20240107-aarch64-apple-darwin.tar.zst",
+        "size": 122215378,
+        "sha256": "ab73534d8cc4ab1767bcee8cf77ca9fb346f1c9866d292fff06b267b9fef9b77",
+        "version": "17.0.6+20240107",
     },
     "llvm-x86_64-macos": {
-        "url": "https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20230506/llvm-16.0.3+20230506-x86_64-apple-darwin.tar.zst",
-        "size": 123709633,
-        "sha256": "59b9d16f27383444ec458eb116778e871c2e23e92f6704c319f7ab5747a3e26e",
-        "version": "16.0.3+20230506",
+        "url": "https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20240107/llvm-17.0.6+20240107-x86_64-apple-darwin.tar.zst",
+        "size": 127474959,
+        "sha256": "3b78fb70806493ad423b19ec8c2e4fa28963bd0c8a4e01fd41f6ad651382ece8",
+        "version": "17.0.6+20240107",
     },
     "m4": {
         "url": "https://ftp.gnu.org/gnu/m4/m4-1.4.19.tar.xz",