make-binaries: Omit unnecessary glibc setting

The CT_GLIBC_KERNEL_VERSION_NONE option is about the minimum kernel
version supported by the toolchain's glibc.  The default is to stick to
the version of the kernel headers, which should be just fine.

tools/make-binaries

@@ -273,7 +273,6 @@ create_gnu_config()
 
 	cat >>"$file" <<-'EOF'
 		CT_GLIBC_V_2_19=y
-		CT_GLIBC_KERNEL_VERSION_NONE=y
 	EOF
 }
 #.