gcc: fix MIPS cross-compile when GCC 4.x is used

toolchain/gcc/Makefile

@@ -145,9 +145,11 @@ ifneq ($(ADK_TARGET_INSTRUCTION_SET),)
 GCC_CONFOPTS+=		--with-mode=$(ADK_TARGET_INSTRUCTION_SET)
 endif
 
+ifneq ($(ADK_TOOLCHAIN_GCC_4),y)
 ifneq ($(ADK_TARGET_NAN_MODE),)
 GCC_CONFOPTS+=		--with-nan=$(ADK_TARGET_NAN_MODE)
 endif
+endif
 
 # .symver is broken for Blackfin, simple C++ apps fail to link
 ifeq ($(ADK_TARGET_ARCH_BFIN),y)