lavfi: port boxblur filter from libmpcodecs

With the following additions:
* support to gray format
* support to yuva420p format
* parametric luma/chroma/alpha radius
* consistency check on the radius values, avoid crashes with invalid values

Signed-off-by: Anton Khirnov <anton@khirnov.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/configure b/configure
index dbbb86c095..720b625237 100755
--- a/configure
+++ b/configure
@@ -1480,6 +1480,7 @@ udp_protocol_deps="network"
 
 # filters
 blackframe_filter_deps="gpl"
+boxblur_filter_deps="gpl"
 cropdetect_filter_deps="gpl"
 drawtext_filter_deps="libfreetype"
 frei0r_filter_deps="frei0r dlopen strtok_r"