Revert "Add frule and rrule for jl_has_free_typevars"

This reverts commit f742b65.

Author: sunxd3

src/rrules/foreigncall.jl

@@ -254,30 +254,6 @@ function rrule!!(
     return zero_fcodual(y), NoPullback(ntuple(_ -> NoRData(), 8))
 end
 
-function frule!!(
-    ::Dual{typeof(_foreigncall_)},
-    ::Dual{Val{:jl_has_free_typevars}},
-    ::Dual{Val{Int32}}, # return type
-    ::Dual{Tuple{Val{Any}}}, # arg types
-    ::Dual{Val{0}}, # number of required args
-    ::Dual{Val{:ccall}},
-    t::Dual,
-)
-    return zero_dual(ccall(:jl_has_free_typevars, Int32, (Any,), primal(t)))
-end
-function rrule!!(
-    ::CoDual{typeof(_foreigncall_)},
-    ::CoDual{Val{:jl_has_free_typevars}},
-    ::CoDual{Val{Int32}}, # return type
-    ::CoDual{Tuple{Val{Any}}}, # arg types
-    ::CoDual{Val{0}}, # number of required args
-    ::CoDual{Val{:ccall}},
-    t::CoDual,
-)
-    y = ccall(:jl_has_free_typevars, Int32, (Any,), primal(t))
-    return zero_fcodual(y), NoPullback(ntuple(_ -> NoRData(), 7))
-end
-
 @is_primitive MinimalCtx Tuple{typeof(deepcopy),Any}
 frule!!(::Dual{typeof(deepcopy)}, x::Dual) = Dual(deepcopy(primal(x)), deepcopy(tangent(x)))
 function rrule!!(::CoDual{typeof(deepcopy)}, x::CoDual)
@@ -473,20 +449,6 @@ function derived_rule_test_cases(rng_ctor, ::Val{:foreigncall})
             TypeVar(:a),
             Real,
         ),
-        (
-            false,
-            :none,
-            nothing,
-            t -> ccall(:jl_has_free_typevars, Int32, (Any,), t),
-            Float64,
-        ),
-        (
-            false,
-            :none,
-            nothing,
-            t -> ccall(:jl_has_free_typevars, Int32, (Any,), t),
-            Vector{Float64},
-        ),
         (
             true,
             :none,