gdb: bump to 7.3.1

this version fixes compilation issue on some old build systems like
openSUSE 10.3 saying some host libraries were too old

[Peter: drop bugfix number from config name, similar to kernel-headers]
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

toolchain/gdb/Config.in

@@ -59,6 +59,11 @@ choice
 		depends on !BR2_bfin
 		select BR2_PTHREAD_DEBUG if !BR2_PTHREADS_NONE
 
+	config BR2_GDB_VERSION_7_3
+		bool "gdb 7.3.x"
+		depends on !BR2_bfin
+		select BR2_PTHREAD_DEBUG if !BR2_PTHREADS_NONE
+
 endchoice
 
 config BR2_GDB_VERSION
@@ -69,3 +74,4 @@ config BR2_GDB_VERSION
 	default "6.8"      if BR2_GDB_VERSION_6_8
 	default "7.0.1"    if BR2_GDB_VERSION_7_0_1
 	default "7.1"      if BR2_GDB_VERSION_7_1
+	default "7.3.1"    if BR2_GDB_VERSION_7_3