chan_sip: Add case for FLASH control frames so that we don't display a warning.

chan_sip channels can receive flash control frames when connected to analog
phones and possibly for other reasons. There really isn't a reason to warn when
these frames are received, we can safely ignore them.

Patches:
    dahdi_sip_flash.diff uploaded by Jonathan Rose (license 6182)
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Merged revisions 369750 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 369751 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@369764 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -7199,6 +7199,8 @@ static int sip_indicate(struct ast_channel *ast, int condition, const void *data
 		break;
 	case AST_CONTROL_UPDATE_RTP_PEER: /* Absorb this since it is handled by the bridge */
 		break;
+	case AST_CONTROL_FLASH: /* Absorb this since it is irrelevant to SIP. */
+		break;
 	case AST_CONTROL_PVT_CAUSE_CODE: /* these should be handled by the code in channel.c */
 	case -1:
 		res = -1;