fix stack base detection on hppa

Forwarded: not-yet
Last-Update: 2018-12-18

Gbp-Pq: Name hppa_stackbase.diff

src/3rdparty/javascriptcore/JavaScriptCore/runtime/Collector.cpp

@@ -672,7 +672,12 @@ static inline void* currentThreadStackBase()
         pthread_attr_destroy(&sattr);
         stackThread = thread;
     }
+#if defined(__hppa__)
+    // Stack grows up.
+    return static_cast<char*>(stackBase);
+#else
     return static_cast<char*>(stackBase) + stackSize;
+#endif
 #else
 #error Need a way to get the stack base on this platform
 #endif