[Kernel] improve error message related to GCC/MSVC machdeps

src/kernel_internals/typing/cabs2cil.ml

src/kernel_services/ast_queries/cil.ml

src/kernel_services/ast_queries/cil.mli

src/plugins/value/domains/cvalue/cvalue_init.ml

tests/misc/oracle/function_ptr_alignof.res.oracle

tests/misc/oracle/function_ptr_sizeof.res.oracle

...s/syntax/oracle/flexible_array_member_invalid5.res.oracle

tests/syntax/oracle/sizeof_void.0.res.oracle

tests/value/oracle/array_zero_length.2.res.oracle

tests/value/oracle/empty_base.1.res.oracle