define wxHAS_ATOMIC_OPS only if native implementation is available; use fewer loop iterations in the test if it isn't as otherwise the test takes way too long to run

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@53954 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/atomic.h

@@ -17,14 +17,23 @@
 /**
     This function increments @a value in an atomic manner.
 
+    Whenever possible wxWidgets provides an efficient, CPU-specific,
+    implementation of this function. If such implementation is available, the
+    symbol wxHAS_ATOMIC_OPS is defined. Otherwise this function still exists
+    but is implemented in a generic way using a critical section which can be
+    prohibitively expensive for use in performance-sensitive code.
+
     @header{wx/atomic.h}
 */
 void wxAtomicInc(wxAtomicInt& value);
 
 /**
-    This function decrements value in an atomic manner. Returns 0 if value is 0
-    after decrementation or any non-zero value (not necessarily equal to the
-    value of the variable) otherwise.
+    This function decrements value in an atomic manner.
+
+    Returns 0 if value is 0 after decrement or any non-zero value (not
+    necessarily equal to the value of the variable) otherwise.
+
+    @see wxAtomicInc
 
     @header{wx/atomic.h}
 */