#71 lame: invalid sample rate -> segmentation fault

[Maks]

See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=775959

Attached patch is for current trunk.

For 3.99.5:
+ if (gfp->samplerate_in < 0) {
+ freegfc(gfc);
+ gfp->internal_flags = NULL;
+ return -1;
+ }