avcodec/libaomenc,cosmetics: fix a typo

tradeof -> trade-off
Signed-off-by: James Zern <jzern@google.com>

libavcodec/libaomenc.c

@@ -1097,7 +1097,7 @@ static const AVOption options[] = {
     { "enable-global-motion",  "Enable global motion",             OFFSET(enable_global_motion), AV_OPT_TYPE_BOOL, {.i64 = -1}, -1, 1, VE},
     { "enable-intrabc",  "Enable intra block copy prediction mode", OFFSET(enable_intrabc), AV_OPT_TYPE_BOOL, {.i64 = -1}, -1, 1, VE},
     { "enable-restoration", "Enable Loop Restoration filtering", OFFSET(enable_restoration), AV_OPT_TYPE_BOOL, {.i64 = -1}, -1, 1, VE},
-    { "usage",           "Quality and compression efficiency vs speed tradeof", OFFSET(usage), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, VE, "usage"},
+    { "usage",           "Quality and compression efficiency vs speed trade-off", OFFSET(usage), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, VE, "usage"},
     { "good",            "Good quality",      0, AV_OPT_TYPE_CONST, {.i64 = 0 /* AOM_USAGE_GOOD_QUALITY */}, 0, 0, VE, "usage"},
     { "realtime",        "Realtime encoding", 0, AV_OPT_TYPE_CONST, {.i64 = 1 /* AOM_USAGE_REALTIME */},     0, 0, VE, "usage"},
     { "tune",            "The metric that the encoder tunes for. Automatically chosen by the encoder by default", OFFSET(tune), AV_OPT_TYPE_INT, {.i64 = -1}, -1, AOM_TUNE_SSIM, VE, "tune"},