lttng-tools: Filter out regression testsuite on musl systems

regression testsuite does not run to finish on musl systems, some of
the issues seen

* python is OOM'ing which is fixed by asking for 8G memory for qemu
* It hits the timeout limits of ptest-runner even -t 2400 does not finish it
* Use make -j1 and running run-ptest script directly ( outside
  ptest-runner to avoid timeout limit) causes it to run forever

Lets disable this testsuite for musl systems for now.

(From OE-Core rev: b97dcec2bce26f0eb2a9a842cd20637ab1f17d0d)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-kernel/lttng/lttng-tools_2.14.0.bb

@@ -205,6 +205,11 @@ do_install_ptest () {
     done
 }
 
+do_install_ptest:append:libc-musl () {
+    # filter-out running regression testsuite on musl systems, it hangs
+    sed -i -e '$a\' -e 'SUBDIRS := $(filter-out regression,$(SUBDIRS))' ${D}${PTEST_PATH}/tests/Makefile
+}
+
 INHIBIT_PACKAGE_STRIP_FILES = "\
     ${PKGD}${PTEST_PATH}/tests/utils/testapp/userspace-probe-elf-binary/userspace-probe-elf-binary \
     ${PKGD}${PTEST_PATH}/tests/utils/testapp/userspace-probe-elf-binary/.libs/userspace-probe-elf-binary \