auto merge of #8779 : brson/rust/macsupp, r=thestinger

This callstack changed when the FFI did. I am still a little frightened by
this suppression.

cc #8253

src/etc/x86.supp

@@ -512,6 +512,5 @@
    fun:uv__platform_loop_init
    fun:uv__loop_init
    fun:uv_loop_new
-   fun:rust_uv_loop_new__c_stack_shim
    ...
 }