I changed PCHUsageMode to NoSharedPCHs or Default in Build.cs and everything was as 4.15.
But in 4.15 UseExplicitOrSharedPCHs works.
// this do not work for me
PCHUsage = PCHUsageMode.UseExplicitOrSharedPCHs;
PCHUsage = PCHUsageMode.UseSharedPCHs;
// work the same way
PCHUsage = PCHUsageMode.NoSharedPCHs;
PCHUsage = PCHUsageMode.Default;
1> Performing 3 actions (2 in parallel)
1> ClientGameMode.cpp
1> [2/3] Link UE4Editor-Client-7868.dll
1> [3/3] Link UE4Editor-Client-7695.lib
…
1> Total build time:** 20,27 seconds** (Local executor: 0,00 seconds)
…
========== Build: 1 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========