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)

# Build script for m4

CT_M4_VERSION=1.4.13

do_companion_tools_m4_get() {

    CT_GetFile "m4-${CT_M4_VERSION}" \

               {ftp,http}://ftp.gnu.org/gnu/m4

}

do_companion_tools_m4_extract() {

    CT_Extract "m4-${CT_M4_VERSION}"

    CT_Patch "m4" "${CT_M4_VERSION}"

}

do_companion_tools_m4_build() {

    CT_DoStep EXTRA "Installing m4"

    mkdir -p "${CT_BUILD_DIR}/build-m4"

    CT_Pushd "${CT_BUILD_DIR}/build-m4"

    CT_DoExecLog CFG \

    "${CT_SRC_DIR}/m4-${CT_M4_VERSION}/configure" \

        --prefix="${CT_TOOLS_OVERIDE_DIR}"

    CT_DoExecLog ALL make

    CT_DoExecLog ALL make install

    CT_Popd

    CT_EndStep

}