Features: Record C/CXX dialect flags for GNU 4.6.

This release was prior to standardization of C11/CXX11.

Modules/Compiler/GNU-C.cmake

@@ -1,15 +1,20 @@
 include(Compiler/GNU)
 __compiler_gnu(C)
 
-if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.7)
+if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.6)
   set(CMAKE_C90_STANDARD_COMPILE_OPTION "-std=c90")
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION "-std=gnu90")
 
   set(CMAKE_C99_STANDARD_COMPILE_OPTION "-std=c99")
   set(CMAKE_C99_EXTENSION_COMPILE_OPTION "-std=gnu99")
+endif()
 
+if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.7)
   set(CMAKE_C11_STANDARD_COMPILE_OPTION "-std=c11")
   set(CMAKE_C11_EXTENSION_COMPILE_OPTION "-std=gnu11")
+elseif (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.6)
+  set(CMAKE_C11_STANDARD_COMPILE_OPTION "-std=c1x")
+  set(CMAKE_C11_EXTENSION_COMPILE_OPTION "-std=gnu1x")
 endif()
 
 if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 5.0)

Modules/Compiler/GNU-CXX.cmake

@@ -11,7 +11,7 @@ else()
   endif()
 endif()
 
-if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.7)
+if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.6)
   # Supported since 4.3
   set(CMAKE_CXX98_STANDARD_COMPILE_OPTION "-std=c++98")
   set(CMAKE_CXX98_EXTENSION_COMPILE_OPTION "-std=gnu++98")
@@ -20,7 +20,10 @@ endif()
 if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.7)
   set(CMAKE_CXX11_STANDARD_COMPILE_OPTION "-std=c++11")
   set(CMAKE_CXX11_EXTENSION_COMPILE_OPTION "-std=gnu++11")
+elseif (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.6)
   # 4.3 supports 0x variants
+  set(CMAKE_CXX11_STANDARD_COMPILE_OPTION "-std=c++0x")
+  set(CMAKE_CXX11_EXTENSION_COMPILE_OPTION "-std=gnu++0x")
 endif()
 
 if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9)