lttng-tools: no need to delete libxml.m4

The configure.ac uses pkg-config now and this macro doesn't exist in the tarball
anymore, so remove the deletion.

(From OE-Core rev: 371ec2cb0ed5b04082b29b949cb831d69a8ebb32)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-kernel/lttng/lttng-tools_2.9.3.bb

@@ -50,11 +50,6 @@ FILES_${PN}-dev += "${PYTHON_SITEPACKAGES_DIR}/*.la"
 INSANE_SKIP_${PN} = "libexec dev-so"
 INSANE_SKIP_${PN}-dbg = "libexec"
 
-do_configure_prepend () {
-    # Delete a shipped m4 file that overrides our patched one
-    rm -f ${S}/m4/libxml.m4
-}
-
 do_install_ptest () {
     for f in Makefile tests/Makefile tests/utils/utils.sh ; do
         install -D "${B}/$f" "${D}${PTEST_PATH}/$f"