Merge pull request #1734 from rust-lang/revert-1687-patch-1

Revert "Update function-pointer.md for stabilization of `extended_varargs_abi_support`"

src/types/function-pointer.md

diff --git a/src/types/function-pointer.md b/src/types/function-pointer.md
index 21a3982..9fcbe34 100644
--- a/src/types/function-pointer.md
+++ b/src/types/function-pointer.md
@@ -39,14 +39,7 @@
 
 r[type.fn-pointer.constraint-variadic]
 Variadic parameters can only be specified with [`extern`] function types with
-these calling conventions:
-* `C`
-* `cdecl`
-* `system`
-* `aapcs`
-* `sysv64`
-* `win64`
-* `efiapi`
+the `"C"` or `"cdecl"` calling convention.
 
 An example where `Binop` is defined as a function pointer type: