avutil/tests/.gitignore: Add recently added test tools

Reviewed-by: Marvin Scholz <epirat07@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavutil/tests/.gitignore

@@ -33,6 +33,7 @@
 /lls
 /log
 /lzo
+/mathematics
 /md5
 /murmur3
 /opt
@@ -43,7 +44,9 @@
 /pixfmt_best
 /random_seed
 /rational
+/rc4
 /ripemd
+/samplefmt
 /sha
 /sha512
 /side_data_array
@@ -51,6 +54,7 @@
 /spherical
 /stereo3d
 /tea
+/timecode
 /tree
 /twofish
 /utf8