CI: Add native64 to CI

- Test native64 like native in murdock
- Add native64 to "Platform: native" in github labeler
- Add "BUILDTEST_MCU_GROUP == x86_64" to `dist/tools/ci/build_and_test.sh`

.github/labeler.yml

@@ -118,7 +118,9 @@
 
 "Platform: native":
   - "boards/native/**/*"
+  - "boards/native64/**/*"
   - "cpu/native/**/*"
+  - "makefiles/arch/native.inc.mk"
 
 "Platform: ARM":
   - "cpu/arm7_common/**/*"

.murdock

@@ -15,6 +15,7 @@ hifive1b
 msb-430
 msba2
 native
+native64
 nrf52840dk
 qn9080dk
 samr21-xpro
@@ -38,7 +39,7 @@ esac
 
 # temporarily disabling llvm builds until https://github.com/RIOT-OS/RIOT/pull/15595
 # is in
-: ${TEST_BOARDS_LLVM_COMPILE:="iotlab-m3 native nrf52dk mulle nucleo-f401re samr21-xpro slstk3402a"}
+: ${TEST_BOARDS_LLVM_COMPILE:="iotlab-m3 native native64 nrf52dk mulle nucleo-f401re samr21-xpro slstk3402a"}
 
 : ${TEST_WITH_CONFIG_SUPPORTED:="examples/suit_update tests/drivers/at86rf2xx_aes"}
 
@@ -380,9 +381,9 @@ compile() {
             EMULATED=0
         fi
 
-        if [ $RUN_TESTS -eq 1 -o "$board" = "native" -o "$EMULATED" = "1" ]; then
+        if [ $RUN_TESTS -eq 1 -o "$board" = "native" -o "$board" = "native64" -o "$EMULATED" = "1" ]; then
             if [ -f "${BINDIR}/.test" ]; then
-                if [ "$board" = "native" -o "${EMULATED}" = "1" ]; then
+                if [ "$board" = "native" -o "$board" = "native64" -o "${EMULATED}" = "1" ]; then
                     # For native, we can run the test on the worker that also
                     # compiled it (`make -C${appdir} test`).
                     # "dwq-localjob" allows using some (locally run) command's

dist/tools/ci/build_and_test.sh

@@ -54,6 +54,11 @@ then
         set_result $?
     fi
 
+    if [ "$BUILDTEST_MCU_GROUP" == "x86_64" ]
+    then
+        make -C ./tests/unittests all test BOARD=native64 TERMPROG='gdb -batch -ex r -ex bt $(ELF)' || exit
+        set_result $?
+    fi
 
     ./dist/tools/compile_test/compile_test.py $BASE_BRANCH
     set_result $?

dist/tools/compile_test/compile_like_murdock.py

@@ -92,6 +92,7 @@
     'microbit',
     'mulle',
     'native',
+    'native64',
     'nrf52840dk',
     'nrf9160dk',
     'nucleo-f072rb',