debug/ltrace: fix building for mips

ltrace 0.5.3 currently fails to build for target mips because MY_TARGET
(introduced by patches/ltrace/0.5.3/150-allow-configurable-arch.patch)
is set to 'mips' via CT_ARCH, while the mips specific stuff in ltrace
(0.5.3) is stored under sysdeps/linux-gnu/mipsel:

result: *** No rule to make target `mips/arch.h', needed by `sysdep.h'.
Stop.

The following patch fixes this issue

Signed-off-by: "Horst Kronstorfer" <horst.kronstorfer@aon.at>
[yann.morin.1998@anciens.enib.fr: reformat commit log]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
(transplanted from 2115901c7f07181d92ddbd7dd7ebeaa72e4fb176)

# Menu for the native gdbserver

config GDB_GDBSERVER

    bool

    prompt "gdbserver"

    default n

    depends on ! BARE_METAL

    help

      Build and install a gdbserver for the target, to run on the target.

if GDB_GDBSERVER

config GDB_GDBSERVER_STATIC

    bool

    prompt "Build a static gdbserver"

    default y

    help

      In case you have trouble with dynamic loading of shared libraries,

      you will find that a static gdbserver comes in handy.

endif # GDB_GDBSERVER

if BARE_METAL

comment "In bare-metal, you'll need to   "

comment "provide your own gdbserver stub."

endif # BARE_METAL