qapi-gen: New common driver for code and doc generators

Whenever qapi-schema.json changes, we run six programs eleven times to
update eleven files.  Similar for qga/qapi-schema.json.  This is
silly.  Replace the six programs by a single program that spits out
all eleven files.

The programs become modules in new Python package qapi, along with the
helper library.  This requires moving them to scripts/qapi/.  While
moving them, consistently drop executable mode bits.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180211093607.27351-9-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
[eblake: move change to one-line 'blurb' earlier in series, mention mode
bit change as intentional, update qapi-code-gen.txt to match actual
generated events.c file]
Signed-off-by: Eric Blake <eblake@redhat.com>

scripts/qapi-gen.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python
+# QAPI generator
+#
+# This work is licensed under the terms of the GNU GPL, version 2 or later.
+# See the COPYING file in the top-level directory.
+
+import sys
+from qapi.common import parse_command_line, QAPISchema
+from qapi.types import gen_types
+from qapi.visit import gen_visit
+from qapi.commands import gen_commands
+from qapi.events import gen_events
+from qapi.introspect import gen_introspect
+from qapi.doc import gen_doc
+
+
+def main(argv):
+    (input_file, output_dir, prefix, opts) = \
+        parse_command_line('bu', ['builtins', 'unmask-non-abi-names'])
+
+    opt_builtins = False
+    opt_unmask = False
+
+    for o, a in opts:
+        if o in ('-b', '--builtins'):
+            opt_builtins = True
+        if o in ('-u', '--unmask-non-abi-names'):
+            opt_unmask = True
+
+    schema = QAPISchema(input_file)
+
+    gen_types(schema, output_dir, prefix, opt_builtins)
+    gen_visit(schema, output_dir, prefix, opt_builtins)
+    gen_commands(schema, output_dir, prefix)
+    gen_events(schema, output_dir, prefix)
+    gen_introspect(schema, output_dir, prefix, opt_unmask)
+    gen_doc(schema, output_dir, prefix)
+
+
+if __name__ == '__main__':
+    main(sys.argv)