make alpha/x86_64 selectable options and export architecture endian so we can use it in uclibc config setup

Config.in

@@ -12,6 +12,9 @@ choice
 	help
 	  Stuff
 
+config BR2_alpha
+	bool "alpha"
+
 config BR2_arm
 	bool "arm"
 
@@ -42,6 +45,9 @@ config BR2_sh
 config BR2_sparc
 	bool "sparc"
 
+config BR2_x86_64
+	bool "x86_64"
+
 endchoice
 
 #
@@ -77,6 +83,7 @@ endchoice
 
 config BR2_ARCH
 	string
+	default "alpha"		if BR2_alpha
 	default "arm"		if BR2_arm
 	default "armeb"		if BR2_armeb
 	default "cris"		if BR2_cris
@@ -92,6 +99,15 @@ config BR2_ARCH
 	default "sh4"		if BR2_sh4
 	default "sh4eb"		if BR2_sh4eb
 	default "sparc"		if BR2_sparc
+	default "x86_64"	if BR2_x86_64
+
+config BR2_ENDIAN
+	string
+	default "LITTLE" if BR2_arm || BR2_cris || BR2_i386 || BR2_mipsel || \
+	                    BR2_sh3 || BR2_sh4 || BR2_x86_64
+	default "BIG"    if BR2_alpha || BR2_armeb || BR2_m68k || BR2_mips || \
+	                    BR2_powerpc || BR2_sh2a_nofpueb || BR2_sh2eb || \
+	                    BR2_sh3eb || BR2_sh4eb || BR2_sparc
 
 menu "Build options"