[flang] Missing diagnostic on missing DEFERRED attribute

[DanielCChen]

Consider the following code:

module m1
   type:: base
      integer :: id
   contains
      procedure, nopass :: print1 => printbase
   end type

   type, extends(base), abstract :: child
   contains
      procedure(printif), deferred,  nopass :: print1
   end type

   interface
      subroutine printif()
      end subroutine
   end interface

contains
   subroutine printbase()
      print *,"hello"
   end subroutine
end module

print1 in type child has the DEFERRED attribute but its overridden print1 in type base does not.
This usage should be diagnosed.

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: Daniel Chen (DanielCChen)

Consider the following code: ``` module m1 type:: base integer :: id contains procedure, nopass :: print1 => printbase end type

type, extends(base), abstract :: child
contains
procedure(printif), deferred, nopass :: print1
end type

interface
subroutine printif()
end subroutine
end interface

contains
subroutine printbase()
print *,"hello"
end subroutine
end module

`print1` in type `child` has the `DEFERRED` attribute but its overridden `print1` in type `base` does not.
This usage should be diagnosed.
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