
The patch fixes Function Multi Versioning features detection by ifunc resolver on Android API levels < 30. Ifunc hwcaps parameters are not supported on Android API levels 23-29, so all CPU features are set unsupported if they were not initialized before ifunc resolver call. There is no support for ifunc on Android API levels < 23, so Function Multi Versioning is disabled in this case. Also use two underscore prefix for FMV runtime support functions to avoid conflict with user program ones. Differential Revision: https://reviews.llvm.org/D158641