Revert "[meson] Use pathlib in gen-harfbuzzcc.py"

This reverts commit eaf7e5686c.

Fixes https://github.com/harfbuzz/harfbuzz/issues/3776

No idea what is going on, but lets restore the old code.

src/gen-harfbuzzcc.py

@@ -2,24 +2,23 @@
 
 "This tool is intended to be used from meson"
 
-import shutil
-import sys
-
-from pathlib import Path
+import os, sys, shutil
 
 if len (sys.argv) < 3:
 	sys.exit (__doc__)
 
-OUTPUT = Path (sys.argv[1])
-CURRENT_SOURCE_DIR = Path (sys.argv[2])
+OUTPUT = sys.argv[1]
+CURRENT_SOURCE_DIR = sys.argv[2]
 
 # make sure input files are unique
-sources = [Path(x) for x in sorted(set(sys.argv[3:]))]
+sources = sorted(set(sys.argv[3:]))
 
 with open (OUTPUT, "wb") as f:
-	f.write ("".join ('#include "{}"\n'.format (p.resolve ().relative_to (CURRENT_SOURCE_DIR)) for p in sources if p.suffix == ".cc").encode ())
+	f.write ("".join ('#include "{}"\n'.format (os.path.relpath (os.path.abspath (x), CURRENT_SOURCE_DIR)) for x in sources if x.endswith (".cc")).encode ())
 
 # copy it also to the source tree, but only if it has changed
-baseline = CURRENT_SOURCE_DIR / OUTPUT.name
-if baseline.read_bytes() != OUTPUT.read_bytes():
-	shutil.copyfile (OUTPUT, baseline)
+baseline_filename = os.path.join (CURRENT_SOURCE_DIR, os.path.basename (OUTPUT))
+with open(baseline_filename, "rb") as baseline:
+	with open(OUTPUT, "rb") as generated:
+		if baseline.read() != generated.read():
+			shutil.copyfile (OUTPUT, baseline_filename)