Remove stale cglobal(:jl_tls_states) test (JuliaLang#43161)

* Remove stale `cglobal(:jl_tls_states)` test
* Remove `jl_threading_enabled`
* The function `threadingOn()` in `julia-config.jl` is the only reference
other than the tests just removed. It looks like `threadingOn` itself is
not used anywhere in the script.

contrib/julia-config.jl

@@ -11,8 +11,6 @@ const options = [
  "--framework"
 ];
 
-threadingOn() = ccall(:jl_threading_enabled, Cint, ()) != 0
-
 function shell_escape(str)
  str = replace(str, "'" => "'\''")
  return "'$str'"

src/jl_exported_funcs.inc

@@ -460,7 +460,6 @@
  XX(jl_task_stack_buffer) \
  XX(jl_test_cpu_feature) \
  XX(jl_threadid) \
- XX(jl_threading_enabled) \
  XX(jl_throw) \
  XX(jl_throw_out_of_memory_error) \
  XX(jl_too_few_args) \

src/sys.c

@@ -916,11 +916,6 @@ JL_DLLEXPORT size_t jl_maxrss(void)
 #endif
 }
 
-JL_DLLEXPORT int jl_threading_enabled(void)
-{
- return 1;
-}
-
 #ifdef __cplusplus
 }
 #endif

test/threads_exec.jl

@@ -517,15 +517,6 @@ if cfunction_closure
  test_thread_cfunction()
 end
 
-# Compare the two ways of checking if threading is enabled.
-# `jl_tls_states` should only be defined on non-threading build.
-if ccall(:jl_threading_enabled, Cint, ()) == 0
- @test nthreads() == 1
- cglobal(:jl_tls_states) != C_NULL
-else
- @test_throws ErrorException cglobal(:jl_tls_states)
-end
-
 function test_thread_range()
  a = zeros(Int, nthreads())
  @threads for i in 1:threadid()