Meson: install symlinks or copies of binaries

On most system symlinks are fine, but on windows symlinks are tricky at
best, or unsupported for older versions of windows. To avoid those
problems we'll just copy the binary if the host or build machine is
windows. This uses a small helper python script to make this all
easier to use and understand.

install_links.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+
+"""Create a symlink or a copy of an installed file."""
+
+import argparse
+import os
+import shutil
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('bindir')
+    parser.add_argument('source')
+    parser.add_argument('dest', nargs='+')
+    parser.add_argument('--use-links', action='store_true')
+    args = parser.parse_args()
+
+    os.chdir(os.environ['MESON_INSTALL_DESTDIR_PREFIX'])
+    os.chdir(args.bindir)
+
+    # Windows doesn't really use symlinks, just copy in that case. Windows
+    # before vista (xp) doesn't have symlinks at all.
+    if args.use_links:
+        func = os.symlink
+        verb = 'Linking'
+    else:
+        func = shutil.copy
+        verb = 'Copying'
+
+    # at least os.symlink will fail if the destination already exists, just
+    # remove the dest if it already exists.
+    for dest in args.dest:
+        if os.path.exists(dest):
+            os.unlink(dest)
+
+        func(args.source, dest)
+        print('{} {} to {}'.format(verb, args.source, dest))
+
+
+if __name__ == "__main__":
+    main()