Merge changes from topic 'missing-proto' into nextgenv2

* changes:
  vp10/encoder/rdopt.c: make a function static
  vp10/encoder/rd.c: make a function static
  vp10_convolve_ssse3.c: make some functions static
  vp10/encoder/bitstream.[hc]: correct a prototype
  vp10/common/idct.h: add some missing prototypes
  highbd_quantize_intrin_sse2.c: add missing rtcd include
  vp10: add some missing includes