configs: provide a fragment to enable gdb for qemu

Adding a fragment to make it easier to know what options is needed to
build a kernel to get the that you can debug in qemu.

First you need to start qemu with flags '-s -S' and then connect with
gdb like below:
$ gdb \
 ./obj-dir/vmlinux -iex 'add-auto-load-safe-path \
 ./obj-dir' -ex 'target remote localhost:1234'

Signed-off-by: Anders Roxell <[email protected]>

kernel/configs/qemu-gdb.config

@@ -0,0 +1,7 @@
+# Enable debug info for gdb
+# CONFIG_COMPILE_TEST is not set
+CONFIG_DEBUG_INFO=y
+CONFIG_GDB_SCRIPTS=y
+
+# Easier to debug
+# CONFIG_RANDOMIZE_BASE is not set