contrib: update libvpx to 1.7.0

Change-Id: I5234eecf0da678d52edf40758a0bc75814b7cbb8

contrib/src/vpx/SHA512SUMS

 13b7eb515d026b302b8c484d6f06df067feb5aed4ceac953d85fe84fd684dab07e89ddbf80b4f395c6d9127709422156287e5754f49246050b2e18930adb3970  libvpx-v1.6.1.tar.gz
-d593c727ed7b977dbd9d571898d1d8b268e534ba913440316cb9c3b15ede81bd427f22a0f45d2d4c2704b5b9a28a167745a8484fd68d917d3630075d5fa80e40  libvpx-v1.5.0.tar.gz
-a3ce308cf193b80c25a96da467e771a1ab9615f4c12d6c00f14c895b9d455d0c3bf556e3f187bc0e58df1905f1ca59a2ac6fa82bc079311ad22cfd6c422a40a6  libvpx-v1.4.0.tar.gz
+8b3b766b550f8d86907628d7ed88035f9a2612aac21542e0fd5ad35b905eb82cbe1be02a1a24afce7a3bcc4766f62611971f72724761996b392136c40a1e7ff0  libvpx-v1.7.0.tar.gz
+3ad6ce36a9a3b044029c069147d69a24f48d9ef872123a587e728a9e20884b7d75cb052b1aed4a020f06314daa80ea1f78d30b829bf25653367c37ce4fe579fb  libvpx-8d56220599bac036f544fb3e35b6be6f71eeb765.tar.gz
\ No newline at end of file

contrib/src/vpx/rules.mak

 # libvpx
 
-VPX_HASH := v1.6.1
+VPX_HASH := v1.7.0
 VPX_URL := https://github.com/webmproject/libvpx/archive/$(VPX_HASH).tar.gz
 
 $(TARBALLS)/libvpx-$(VPX_HASH).tar.gz: