Add the support for aten::mul operator.

[zheng-ningxin]

Add the support for aten::mul operator.
Signed-off-by: Ningxin Ningxin.Zheng@microsoft.com

[zheng-ningxin]

Issue: #2901

[QuanluZhang]

how XXX_inshape function works when an operator has multiple inputs?

[zheng-ningxin]

XXX_inshape cannot have multiple inputs.
For example a += b + c + d # a, b, c, d are tensors
then the inputs of add_inshape is the result of a+b+c

FYI

>>> class tmp(torch.nn.Module):
...     def forward(self, x):
...             ones = torch.ones_like(x)
...             one_2 = torch.ones_like(x)
...             one_3 = torch.ones_like(x)
...             x += one_2 + one_3+ ones
...             return x
...
>>> graph= torch.jit.trace(tmp, torch.ones(4))
>>> torch._C._jit_pass_inline(graph.graph)
>>> graph.graph
graph(%self : __torch__.torch.nn.modules.module.Module,
      %x : Float(4)):
  %9 : int = prim::Constant[value=6]() # <stdin>:4:0
  %10 : int = prim::Constant[value=0]() # <stdin>:4:0
  %11 : Device = prim::Constant[value="cpu"]() # <stdin>:4:0
  %12 : bool = prim::Constant[value=0]() # <stdin>:4:0
  %13 : None = prim::Constant()
  %ones : Float(4) = aten::ones_like(%x, %9, %10, %11, %12, %13) # <stdin>:4:0
  %15 : int = prim::Constant[value=6]() # <stdin>:5:0
  %16 : int = prim::Constant[value=0]() # <stdin>:5:0
  %17 : Device = prim::Constant[value="cpu"]() # <stdin>:5:0
  %18 : bool = prim::Constant[value=0]() # <stdin>:5:0
  %19 : None = prim::Constant()
  %one_2 : Float(4) = aten::ones_like(%x, %15, %16, %17, %18, %19) # <stdin>:5:0
  %21 : int = prim::Constant[value=6]() # <stdin>:6:0
  %22 : int = prim::Constant[value=0]() # <stdin>:6:0
  %23 : Device = prim::Constant[value="cpu"]() # <stdin>:6:0
  %24 : bool = prim::Constant[value=0]() # <stdin>:6:0
  %25 : None = prim::Constant()
  %one_3 : Float(4) = aten::ones_like(%x, %21, %22, %23, %24, %25) # <stdin>:6:0
  %27 : int = prim::Constant[value=1]() # <stdin>:7:0
  %28 : Float(4) = aten::add(%one_2, %one_3, %27) # <stdin>:7:0
  %29 : int = prim::Constant[value=1]() # <stdin>:7:0
  %30 : Float(4) = aten::add(%28, %ones, %29) # <stdin>:7:0
  %31 : int = prim::Constant[value=1]() # <stdin>:7:0
  %32 : Float(4) = aten::add_(%x, %30, %31) # <stdin>:7:0
  return (%32)