Add VS2019 support

Created by: baptistapedro

````find_program(CMAKE_ASM_COMPILER ml64.exe HINTS "${cl_path}" DOC "path to assembler")
if ("${CMAKE_GENERATOR}" MATCHES "NMake Makefiles")
  set(CMAKE_ASM_COMPILER "ml64.exe")
endif()

else (X64) find_program(CMAKE_ASM_COMPILER ml.exe HINTS "${cl_path}" DOC "path to assembler") if ("${CMAKE_GENERATOR}" MATCHES "NMake Makefiles") set(CMAKE_ASM_COMPILER "ml.exe") endif() endif (X64) if (NOT CMAKE_ASM_COMPILER) message(FATAL_ERROR "assembler not found: required to build") endif (NOT CMAKE_ASM_COMPILER) message(STATUS "Found assembler:````

I am doing cmake -G"Visual Studio 16 Win64" .. and I happen to have an error on the exact line if (NOT CMAKE_ASM_COMPILER) message(FATAL_ERROR "assembler not found: required to build")

I am not sure why it doesnt find the compiler since I'm using the VS with all Build Tools installed, plus the cmake should do it by yourself?