Auto merge of #2387 - erickt:remove-cprng, r=JohnTitor

Revert "fuchsia add getrandom equivalent zx_cprng_draw."

This reverts commit 5b8616e.

I'm on the Fuchsia Rust team, and we would like this reverted for a few reasons. First, these functions are not actually exposed in our `libc`. Instead, it comes from our `libzircon` library. Second, we haven't solidified these APIs, nor have we committed to exactly which library to expose them from.

Instead, we've created https://crates.io/crates/fuchsia-cprng to expose this functionality. This lets us more easily track our downstream users, and help them update if we ever make a breaking change.

cc `@devnexen` and `@anp`

Author: bors

libc-test/semver/fuchsia.txt

@@ -1384,6 +1384,3 @@ utimensat
 vhangup
 vmsplice
 waitid
-zx_cprng_add_entropy
-zx_cprng_draw
-zx_status_t

src/fuchsia/mod.rs

@@ -89,8 +89,6 @@ pub type rlim_t = ::c_ulonglong;
 pub type c_long = i64;
 pub type c_ulong = u64;
 
-pub type zx_status_t = i32;
-
 // FIXME: why are these uninhabited types? that seems... wrong?
 // Presumably these should be `()` or an `extern type` (when that stabilizes).
 #[cfg_attr(feature = "extra_traits", derive(Debug))]
@@ -4231,9 +4229,6 @@ extern "C" {
         >,
         data: *mut ::c_void,
     ) -> ::c_int;
-
-    pub fn zx_cprng_draw(buffer: *mut ::c_void, buffer_size: ::size_t);
-    pub fn zx_cprng_add_entropy(buffer: *const ::c_void, buffer_size: ::size_t) -> ::zx_status_t;
 }
 
 cfg_if! {