Add self-hosted macOS ARM64 Universal Binary runner

Adds a workflow file for building a universal binary with a self hosted runner.
Also adds a Python script to assist with creating the universal binary

tools/mac-universal.py

@@ -0,0 +1,116 @@
+#!/usr/bin/env python3
+"""
+Based on Dolphin's BuildMacOSUniversalBinary.py
+"""
+
+import filecmp
+import glob
+import os
+import shutil
+
+
+def lipo(path0, path1, dst):
+    if subprocess.call(["lipo", "-create", "-output", dst, path0, path1]) != 0:
+        print(f"WARNING: {path0} and {path1} cannot be lipo'd")
+
+        shutil.copy(path0, dst)
+
+
+def recursive_merge_binaries(src0, src1, dst):
+    """
+    Merges two build trees together for different architectures into a single
+    universal binary.
+
+    The rules for merging are:
+
+    1) Files that exist in either src tree are copied into the dst tree
+    2) Files that exist in both trees and are identical are copied over
+       unmodified
+    3) Files that exist in both trees and are non-identical are lipo'd
+    4) Symlinks are created in the destination tree to mirror the hierarchy in
+       the source trees
+    """
+
+    # Check that all files present in the folder are of the same type and that
+    # links link to the same relative location
+    for newpath0 in glob.glob(src0+"/*"):
+        filename = os.path.basename(newpath0)
+        newpath1 = os.path.join(src1, filename)
+        if not os.path.exists(newpath1):
+            continue
+
+        if os.path.islink(newpath0) and os.path.islink(newpath1):
+            if os.path.relpath(newpath0, src0) == os.path.relpath(newpath1, src1):
+                continue
+
+        if os.path.isdir(newpath0) and os.path.isdir(newpath1):
+            continue
+
+        # isfile() can be true for links so check that both are not links
+        # before checking if they are both files
+        if (not os.path.islink(newpath0)) and (not os.path.islink(newpath1)):
+            if os.path.isfile(newpath0) and os.path.isfile(newpath1):
+                continue
+
+        raise Exception(f"{newpath0} and {newpath1} cannot be " +
+                        "merged into a universal binary because they are of " +
+                        "incompatible types. Perhaps the installed libraries" +
+                        " are from different versions for each architecture")
+
+    for newpath0 in glob.glob(src0+"/*"):
+        filename = os.path.basename(newpath0)
+        newpath1 = os.path.join(src1, filename)
+        new_dst_path = os.path.join(dst, filename)
+        if os.path.islink(newpath0):
+            # Symlinks will be fixed after files are resolved
+            continue
+
+        if not os.path.exists(newpath1):
+            if os.path.isdir(newpath0):
+                shutil.copytree(newpath0, new_dst_path)
+            else:
+                shutil.copy(newpath0, new_dst_path)
+
+            continue
+
+        if os.path.isdir(newpath1):
+            os.mkdir(new_dst_path)
+            recursive_merge_binaries(newpath0, newpath1, new_dst_path)
+            continue
+
+        if filecmp.cmp(newpath0, newpath1):
+            shutil.copy(newpath0, new_dst_path)
+        else:
+            lipo(newpath0, newpath1, new_dst_path)
+
+    # Loop over files in src1 and copy missing things over to dst
+    for newpath1 in glob.glob(src1+"/*"):
+        filename = os.path.basename(newpath1)
+        newpath0 = os.path.join(src0, filename)
+        new_dst_path = os.path.join(dst, filename)
+        if (not os.path.exists(newpath0)) and (not os.path.islink(newpath1)):
+            if os.path.isdir(newpath1):
+                shutil.copytree(newpath1, new_dst_path)
+            else:
+                shutil.copy(newpath1, new_dst_path)
+
+    # Fix up symlinks for path0
+    for newpath0 in glob.glob(src0+"/*"):
+        filename = os.path.basename(newpath0)
+        new_dst_path = os.path.join(dst, filename)
+        if os.path.islink(newpath0):
+            relative_path = os.path.relpath(os.path.realpath(newpath0), src0)
+            os.symlink(relative_path, new_dst_path)
+    # Fix up symlinks for path1
+    for newpath1 in glob.glob(src1+"/*"):
+        filename = os.path.basename(newpath1)
+        new_dst_path = os.path.join(dst, filename)
+        newpath0 = os.path.join(src0, filename)
+        if os.path.islink(newpath1) and not os.path.exists(newpath0):
+            relative_path = os.path.relpath(os.path.realpath(newpath1), src1)
+            os.symlink(relative_path, new_dst_path)
+
+
+if __name__ == "__main__":
+    recursive_merge_binaries(sys.argv[1], sys.argv[2], sys.argv[3])
+