Add patches for block-level quant in theora, -O2 on build, and statically link pthread on Windows

r19356_theora_decode_init_error_passing.patch

+commit db092a93aa62fbd42a223c02e9f425a00ca64d2d
+Author: reimar <reimar@9553f0bf-9b14-0410-a0b8-cfaf0461ba5b>
+Date:   Mon Jul 6 09:35:00 2009 +0000
+
+    100l, theora_decode_init must pass on errors from vp3_decode_init
+    
+    
+    git-svn-id: file:///var/local/repositories/ffmpeg/trunk@19356 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b
+
+diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
+index 3f45428..27ea190 100644
+--- a/libavcodec/vp3.c
++++ b/libavcodec/vp3.c
+@@ -2291,6 +2291,7 @@ static av_cold int theora_decode_init(AVCodecContext *avctx)
+     uint8_t *header_start[3];
+     int header_len[3];
+     int i;
++    int ret;
+ 
+     s->theora = 1;
+ 
+@@ -2343,8 +2344,8 @@ static av_cold int theora_decode_init(AVCodecContext *avctx)
+         break;
+   }
+ 
+-    vp3_decode_init(avctx);
+-    return 0;
++    ret = vp3_decode_init(avctx);
++    return ret;
+ }
+ 
+ AVCodec theora_decoder = {