build: when using gcc4 build kernel with c++11

build/jam/ArchitectureRules

@@ -403,6 +403,10 @@ rule KernelArchitectureSetup architecture
 	HAIKU_BOOT_C++FLAGS = $(HAIKU_C++FLAGS_$(architecture)) $(g++BaseFlags) ;
 	HAIKU_BOOT_LINKFLAGS = ;
 
+	if $(gccVersion[1]) >= 4 {
+		HAIKU_KERNEL_C++FLAGS += -std=gnu++11 ;
+	}
+
 	HAIKU_KERNEL_PIC_CCFLAGS = -fno-pic ;
 	HAIKU_KERNEL_PIC_LINKFLAGS = ;
 	HAIKU_KERNEL_ADDON_LINKFLAGS = ;

src/system/kernel/arch/x86/Jamfile

@@ -17,8 +17,6 @@ SEARCH_SOURCE += [ FDirName $(SUBDIR) timers ] ;
 
 local archSpecificSources ;
 if $(TARGET_ARCH) = x86_64 {
-	SubDirC++Flags -std=gnu++11 ;
-
 	SEARCH_SOURCE += [ FDirName $(SUBDIR) 64 ] ;
 	SEARCH_SOURCE += [ FDirName $(SUBDIR) paging 64bit ] ;