COMP: clang++ -Woverloaded-virtual -> spurious warnings? disable for now

- this behaviour changed in clang 2.9 between trunk 122348 and trunk 125662

wmake/rules/linux64Clang/c++

 .SUFFIXES: .C .cxx .cc .cpp
 
-c++WARN     = -Wall -Wextra -Wno-unused-parameter -Wold-style-cast -Wnon-virtual-dtor
+# -Woverloaded-virtual may produce spurious warnings, disable for now
+c++WARN     = -Wall -Wextra -Wno-unused-parameter -Wold-style-cast -Wnon-virtual-dtor -Wno-overloaded-virtual
 
 CC          = clang++ -m64
 

wmake/rules/linuxClang/c++

 .SUFFIXES: .C .cxx .cc .cpp
 
-c++WARN     = -Wall -Wextra -Wno-unused-parameter -Wold-style-cast
+# -Woverloaded-virtual may produce spurious warnings, disable for now
+c++WARN     = -Wall -Wextra -Wno-unused-parameter -Wold-style-cast -Wnon-virtual-dtor -Wno-overloaded-virtual
 
 CC          = clang++ -m32