Revert use of integer_param_regs_saved_in_caller_frame in i386 gdbarch_tdep.

Revert use of integer_param_regs_saved_in_caller_frame in i386 gdbarch_tdep.

This is no longer useful, as it was introduced to reuse the funcall
handling code in amd64-tdep.c in the context of x64-windows. But
we have since then changed the implementations to be completely
independent of each other.

This reverts the non-windows-specific part of the change called:
    amd64-windows: 32 bytes allocated on stack by caller for integer
    parameter regs
(the x64-windows portion has already been reverted)

gdb/ChangeLog:

        Revert:
        * i386-tdep.h (struct gdbarch_tdep): Add new field
        integer_param_regs_saved_in_caller_frame.
        * amd64-tdep.c (amd64_push_dummy_call): Allocate some memory on
        stack if tdep->integer_param_regs_saved_in_caller_frame is set.