whisper: remove MSVC warnings pragmas

[danbev]

This pull request removes the MSVC-specific pragmas from whisper and ggml. These are now handled in the CMakeLists.txt files.

[peardox]

A recently merged commit completely breaks build

It appears to be part of this stuff

Try this...
cmake -B build -DBUILD_SHARED_LIBS=ON -DGGML_BACKEND_DL=ON -DGGML_CPU_ALL_VARIANTS=ON

CMake Error at ggml/CMakeLists.txt:371 (target_compile_options):

if (MSVC)
    set(MSVC_WARNING_FLAGS
        /wd4005  # Macro redefinition
        /wd4244  # Conversion from one type to another type, possible loss of data
        /wd4267  # Conversion from 'size_t' to a smaller type, possible loss of data
    )
    function(disable_msvc_warnings target_name)
        target_compile_options(${target_name} PRIVATE ${MSVC_WARNING_FLAGS})
    endfunction()

    disable_msvc_warnings(ggml-base)
    disable_msvc_warnings(ggml)
    disable_msvc_warnings(ggml-cpu)
endif()

This one did it
55d73a1