system-darwin-ppc.ads (Support_Atomic_Primitives): Set to True only if the word size is 64.

	* system-darwin-ppc.ads (Support_Atomic_Primitives): Set to True only
	if the word size is 64.

From-SVN: r243243

gcc/ada/ChangeLog

+2016-12-05  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* system-darwin-ppc.ads (Support_Atomic_Primitives): Set to True only
+	if the word size is 64.
+
 2016-11-30  Gary Dismukes  <dismukes@adacore.com>
 
 	* sem_prag.adb, sem_ch6.adb: Minor reformatting and typo fixes.

gcc/ada/system-darwin-ppc.ads

@@ -161,7 +161,7 @@ private
    Stack_Check_Probes        : constant Boolean := False;
    Stack_Check_Limits        : constant Boolean := False;
    Support_Aggregates        : constant Boolean := True;
-   Support_Atomic_Primitives : constant Boolean := True;
+   Support_Atomic_Primitives : constant Boolean := Word_Size = 64;
    Support_Composite_Assign  : constant Boolean := True;
    Support_Composite_Compare : constant Boolean := True;
    Support_Long_Shifts       : constant Boolean := True;