Contribs: update Opus to 1.0.1-rc3

(cherry picked from commit fbe2c9bc)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

contrib/src/opus/SHA512SUMS

-62450dd3009c0ca5dd26ce4cb14a4334d5ff4348b1615efab45203a806846f1ba8cbd1e36ea5e565b1b422bd26d814e28678917410b006b0f18c6bf6f0944996  opus-1.0.1-rc.tar.gz
+5024cd81c62d67be1e190a50fe915bcc724ea30dc586caa4d2cc1ba33ac1702e21df40707d55ebf36beb2cfec15d20027ce04297d9ea8cde662064242544cbb8  opus-1.0.1-rc3.tar.gz

contrib/src/opus/rules.mak

 # opus
 
-OPUS_VERSION := 1.0.1-rc
+OPUS_VERSION := 1.0.1-rc3
 
 OPUS_URL := http://downloads.xiph.org/releases/opus/opus-$(OPUS_VERSION).tar.gz