qapi: mcgen() shouldn't indent # lines

Skip preprocessor lines when adding indentation, since that would
likely result in invalid code.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <20180703155648.11933-6-marcandre.lureau@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

scripts/qapi/common.py

@@ -1941,8 +1941,8 @@ def cgen(code, **kwds):
     if indent_level:
         indent = genindent(indent_level)
         # re.subn() lacks flags support before Python 2.7, use re.compile()
-        raw = re.subn(re.compile(r'^.', re.MULTILINE),
-                      indent + r'\g<0>', raw)
+        raw = re.subn(re.compile(r'^(?!(#|$))', re.MULTILINE),
+                      indent, raw)
         raw = raw[0]
     return re.sub(re.escape(eatspace) + r' *', '', raw)