Produce correct init setter method name with winmd output

[RikkiGibson]

roslyn/src/Compilers/CSharp/Portable/Symbols/Synthesized/Records/SynthesizedRecordPropertySymbol.cs

Line 228 in 891fd42

isWinMdOutput: false /* PROTOTYPE */);

Looks like it should be put_PropName not set_PropName in this scenario. I assume it is not hard to check the output kind to figure out what to pass here.

[AlekseyTs]

I believe that after recent changes around implementation of SynthesizedRecordPropertySymbol, change what it derives from, etc. we no longer need to worry about handling naming for accessors. Of course, it would be good to have a test verifying the fact.