[PATCH, Ada, Darwin, PPC] PPC Darwin has stack check probes.

[Iain Sandoe]

On PPC, Darwin uses the same code as other parts of the port, I suspect
that the False was a historical relic.

(perhaps I could have applied this with my Darwin maintainer’s hat, or as obvious,
 but wasn’t sure for the Ada sub-tree)

OK for trunk?
Thanks
Iain

2019-07-01  Iain Sandoe  <iain@sandoe.co.uk>

	* libgnat/system-darwin-ppc.ads: Set Stack_Check_Probes True for
	PPC Darwin.

diff --git a/gcc/ada/libgnat/system-darwin-ppc.ads b/gcc/ada/libgnat/system-darwin-ppc.ads
index d314b66..9adc2de 100644
--- a/gcc/ada/libgnat/system-darwin-ppc.ads
+++ b/gcc/ada/libgnat/system-darwin-ppc.ads
@@ -158,7 +158,7 @@ private
    Preallocated_Stacks       : constant Boolean := False;
    Signed_Zeros              : constant Boolean := True;
    Stack_Check_Default       : constant Boolean := False;
-   Stack_Check_Probes        : constant Boolean := False;
+   Stack_Check_Probes        : constant Boolean := True;
    Stack_Check_Limits        : constant Boolean := False;
    Support_Aggregates        : constant Boolean := True;
    Support_Atomic_Primitives : constant Boolean := Word_Size = 64;