Despite what the docs for MFCreateAVIMediaSink& MFCreateWAVEMediaSink say, they are NOT exported from MF.dll, but instead from MFSRCSNK.dll. Similarly, they aren't in mf.lib, but MFSRCSNK.lib. On the plus side, the include file listed is correct.
It seems odd to export them from that file, since those 2 are almost the only exports from that DLL, but it's been that way since 8.1.