Fix hvcC box writing using incorrect order of operations

[Andrews54757]

Current code:

stream.writeUint8(this.general_profile_space << 6 +
  this.general_tier_flag << 5 +
  this.general_profile_idc);

is equivalent to

stream.writeUint8(this.general_profile_space << (6 +
  this.general_tier_flag) << (5 +
  this.general_profile_idc));

which is incorrect. The correct order of operations are:

stream.writeUint8((this.general_profile_space << 6) +
  (this.general_tier_flag << 5) +
  this.general_profile_idc);

This fixes the file segmenter tool producing invalid hvcC boxes for certain kinds of hvc1 video.

[rbouqueau]

LGTM, merging. Thank you!