build: replace assembly embedding with Python script

This allows Meson to properly track dependencies and re-build the scanner when
editing the dtd. We also stop depending on GNU as' .incbin and make the
embedding less obscure.

Signed-off-by: Simon Ser <contact@emersion.fr>

src/embed.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+
+"""
+Simple C data embedder
+
+License: MIT
+
+Copyright (c) 2020 Simon Ser
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+"""
+
+import sys
+
+if len(sys.argv) != 3:
+    print('usage: ' + sys.argv[0] + ' <filename> <ident>', file=sys.stderr)
+    sys.exit(1)
+
+filename = sys.argv[1]
+ident = sys.argv[2]
+
+with open(filename, 'rb') as f:
+    buf = f.read()
+
+print('static const char ' + ident + '[] = {\n\t', end='')
+for i in range(len(buf)):
+    ch = buf[i:i+1]
+    print('0x' + ch.hex() + ', ', end='')
+print('\n};')