freedreno/registers: Don't re-parse files

Track the files we've parsed, and skip ones we have already seen, if
(for example) we see the same paths imported from imported files.

Additionally having the list of files we have parsed will be useful to
generate a headergen-like top-of-file license comment.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27124>

src/freedreno/registers/gen_header.py

@@ -335,6 +335,7 @@ class Parser(object):
 		self.enums = {}
 		self.variants = set()
 		self.file = []
+		self.xml_files = []
 
 	def error(self, message):
 		parser, filename = self.stack[-1]
@@ -460,6 +461,10 @@ class Parser(object):
 			print("lxml not found, skipping validation", file=sys.stderr)
 
 	def do_parse(self, filename):
+		filepath = os.path.abspath(filename)
+		if filepath in self.xml_files:
+			return
+		self.xml_files.append(filepath)
 		file = open(filename, "rb")
 		parser = xml.parsers.expat.ParserCreate()
 		self.stack.append((parser, filename))