MSVC Warning C4819 (invalid character in source file) when building on system with Windows-1252-incompatible code page

To disabled C4819 warning on non-cp1252 build machine,i need add add_compile_flags("/wd4819") to
Src\cmake\msvc.cmake after line 42 add_compile_flags("/wd4290"),it don't work.

if i add add_compile_flags("/wd4290") to Src\CMakeLists.txt,it work.

if(NOT CMAKE_CROSSCOMPILING)

add_definitions(-DTARGET_${ARCH})

if(MSVC)
if(ARCH STREQUAL "i386")
add_definitions(/D_X86_ /DWIN32 /D_WINDOWS)
endif()
add_definitions(/Dinline=__inline)
add_compile_flags("/wd4819")//// ADD TO THIS LINE
else()
add_compile_flags("-fshort-wchar -Wno-multichar")
endif()