6810672: Comment typos

I have collected some typos I have found while looking at the code.

Reviewed-by: kvn, never

hotspot/src/share/vm/memory/permGen.hpp

@@ -36,7 +36,7 @@ class PermGen : public CHeapObj {
   friend class VMStructs;
  protected:
   size_t _capacity_expansion_limit;  // maximum expansion allowed without a
-                                     // full gc occuring
+                                     // full gc occurring
 
   HeapWord* mem_allocate_in_gen(size_t size, Generation* gen);