swscale: Remove two bogus asserts

(cherry picked from commit b9141aa346b736adffd27e1a98bd12aa7b628a8f)
Signed-off-by: Diego Biurrun <diego@biurrun.de>

Conflicts:
	libswscale/swscale.c
elbg: Fix an assert

It seems the condition was flipped from what was intended.

Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit 2c340596cab981ac842aff7da89d298025c99304)
Signed-off-by: Diego Biurrun <diego@biurrun.de>
mpegvideo: remove last_picture_ptr / h264 assert.

This assert is no longer true since h264 error concealment needs
last_picture_ptr to be set.

Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit 91672504a403556f63492093b892574234f21dd7)
Signed-off-by: Diego Biurrun <diego@biurrun.de>

Conflicts:
	libavcodec/mpegvideo.c