build: integrate DragonFlyBSD into gyp build

PR-URL: #29313
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

Author: devnexen

tools/gyp/pylib/gyp/common.py

@@ -421,6 +421,8 @@ def GetFlavor(params):
     return 'solaris'
   if sys.platform.startswith('freebsd'):
     return 'freebsd'
+  if sys.platform.startswith('dragonfly'):
+    return 'freebsd'
   if sys.platform.startswith('openbsd'):
     return 'openbsd'
   if sys.platform.startswith('netbsd'):