update default versions to gcc 6.2 and binutils 2.27

Makefile

@@ -3,8 +3,8 @@ OUTPUT = $(CURDIR)/output
 SOURCES = sources
 
 CONFIG_SUB_REV = 3d5db9ebe860
-BINUTILS_VER = 2.25.1
-GCC_VER = 5.3.0
+BINUTILS_VER = 2.27
+GCC_VER = 6.2.0
 MUSL_VER = 1.1.15
 GMP_VER = 6.1.1
 MPC_VER = 1.0.3