avcodec/libvpxenc: Update the "cpu-used" options default to match the "speed" alias

Reviewed-by: James Zern <jzern@google.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/libvpxenc.c

@@ -754,7 +754,7 @@ static int vp8_encode(AVCodecContext *avctx, AVPacket *pkt,
 #endif
 
 #define COMMON_OPTIONS \
-    { "cpu-used",        "Quality/Speed ratio modifier",           OFFSET(cpu_used),        AV_OPT_TYPE_INT, {.i64 = INT_MIN}, INT_MIN, INT_MAX, VE}, \
+    { "cpu-used",        "Quality/Speed ratio modifier",           OFFSET(cpu_used),        AV_OPT_TYPE_INT, {.i64 = 1},       INT_MIN, INT_MAX, VE}, \
     { "auto-alt-ref",    "Enable use of alternate reference " \
                          "frames (2-pass only)",                   OFFSET(auto_alt_ref),    AV_OPT_TYPE_INT, {.i64 = -1},      -1,      1,       VE}, \
     { "lag-in-frames",   "Number of frames to look ahead for " \