Add fuzzer corpora.

webrtc/test/fuzzers/corpora/sdp-corpus/firefox-2.sdp

+v=0
+o=mozilla...THIS_IS_SDPARTA-46.0.1 3068771576687940834 0 IN IP4 0.0.0.0
+s=-
+t=0 0
+a=fingerprint:sha-256 AD:87:B3:11:E4:E2:BA:EF:D2:3F:2E:AC:24:57:8E:DC:1F:67:41:29:44:C4:96:E3:62:90:CC:90:59:CA:2C:84
+a=group:BUNDLE sdparta_0 sdparta_1 sdparta_2
+a=ice-options:trickle
+a=msid-semantic:WMS *
+m=audio 9 UDP/TLS/RTP/SAVPF 109
+c=IN IP4 0.0.0.0
+a=recvonly
+a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level
+a=fmtp:109 maxplaybackrate=48000;stereo=1
+a=ice-pwd:ff4c4dc6fe92e1f22d2c10352d8967d5
+a=ice-ufrag:a539544b
+a=mid:sdparta_0
+a=rtcp-mux
+a=rtpmap:109 opus/48000/2
+a=setup:active
+a=ssrc:600995474 cname:{5b598a29-a81b-4ffe-a2c5-507778057e7a}
+m=video 9 UDP/TLS/RTP/SAVPF 120
+c=IN IP4 0.0.0.0
+a=recvonly
+a=fmtp:120 max-fs=12288;max-fr=60
+a=ice-pwd:ff4c4dc6fe92e1f22d2c10352d8967d5
+a=ice-ufrag:a539544b
+a=mid:sdparta_1
+a=rtcp-fb:120 nack
+a=rtcp-fb:120 nack pli
+a=rtcp-fb:120 ccm fir
+a=rtcp-mux
+a=rtpmap:120 VP8/90000
+a=setup:active
+a=ssrc:3480150809 cname:{5b598a29-a81b-4ffe-a2c5-507778057e7a}
+m=application 9 DTLS/SCTP 5000
+c=IN IP4 0.0.0.0
+a=sendrecv
+a=ice-pwd:ff4c4dc6fe92e1f22d2c10352d8967d5
+a=ice-ufrag:a539544b
+a=mid:sdparta_2
+a=sctpmap:5000 webrtc-datachannel 256
+a=setup:active
+a=ssrc:3021788991 cname:{5b598a29-a81b-4ffe-a2c5-507778057e7a}