medians SEGV detected running ASAN tests

[jaromil]

Running #153 detected this:

 "name":"Medians",
 "type":"filter",
 "color_model":"rgba8888",
 "num_params":"2"
},
 "parameters":[
  {"name":"Type","type":"string","explanation":"Choose type of median: Cross5, Square3x3, Bilevel, Diamond3x3, Square5x5, Temp3, Temp5, ArceBI, ML3D, ML3dEX, VarSize"},
  {"name":"Size","type":"double","explanation":"Size for 'var size' type filter"}
 ]
}
AddressSanitizer:DEADLYSIGNAL
=================================================================
==25808==ERROR: AddressSanitizer: SEGV on unknown address (pc 0x7f4516f71119 bp 0x7ffed0b78be0 sp 0x7ffed0b78388 T0)
==25808==The signal is caused by a READ memory access.
==25808==Hint: this fault was caused by a dereference of a high value address (see register values below).  Disassemble the provided pc to learn which register was used.
    #0 0x7f4516f71119  (/lib/x86_64-linux-gnu/libc.so.6+0x167119) (BuildId: def5460e3cee00bfee25b429c97bcc4853e5b3a8)
    #1 0x7f4517478ee9 in strlen ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:389
    #2 0x7f4517b1d7fd in f0r_set_param_value /home/jrml/devel/frei0r/src/filter/medians/medians.c:502
    #3 0x5562c9f98dcd in test_parameters(void*, void (*)(void*, void*, int), void (*)(f0r_param_info*, int), int, int) /home/jrml/devel/frei0r/test/frei0r-run.c:171
    #4 0x5562c9f998ed in main /home/jrml/devel/frei0r/test/frei0r-run.c:370
    #5 0x7f4516e33ca7  (/lib/x86_64-linux-gnu/libc.so.6+0x29ca7) (BuildId: def5460e3cee00bfee25b429c97bcc4853e5b3a8)
    #6 0x7f4516e33d64 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29d64) (BuildId: def5460e3cee00bfee25b429c97bcc4853e5b3a8)
    #7 0x5562c9f98260 in _start (/home/jrml/devel/frei0r/test/frei0r-run+0x3260) (BuildId: a01640d73d2b6b674124aa6fc0fa8fdab427fa36)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/lib/x86_64-linux-gnu/libc.so.6+0x167119) (BuildId: def5460e3cee00bfee25b429c97bcc4853e5b3a8)
==25808==ABORTING