tests: handle cml interactive_sync disabling

[fjmolinas]

Contribution description

If not running the automatic tests then having to enter s on every test can be annoying. This can be easily disable by using DISABLE_MODULE+=test_utils_interactive_sync but this does not work for tests that need to include it directly in the application, add header guards for this.

Testing procedure

• with interactive sync BOARD=pba-d-01-kw2x make -C tests/ps_schedstatistics/ flash term

2020-02-28 17:56:16,923 # main(): This is RIOT! (Version: 2020.04-devel-828-g5fe86-pr_interactive_sync_disable)
2020-02-28 17:56:16,927 # Help: Press s to start test, r to print it is ready
s
2020-02-28 17:56:20,706 # START
2020-02-28 17:56:20,709 # Creating thread #0, next=1
2020-02-28 17:56:20,711 # Creating thread #1, next=2
2020-02-28 17:56:20,713 # Creating thread #2, next=3
2020-02-28 17:56:20,716 # Creating thread #3, next=4
2020-02-28 17:56:20,718 # Creating thread #4, next=0
> 2020-02-28 17:56:21,718 #  

• without interactive sync

DISABLE_MODULE+=test_utils_interactive_sync BOARD=pba-d-01-kw2x make -C tests/ps_schedstatistics/ flash term

2020-02-28 17:57:31,251 #  main(): This is RIOT! (Version: 2020.04-devel-828-g5fe86-pr_interactive_sync_disable)
2020-02-28 17:57:31,253 # Creating thread #0, next=1
2020-02-28 17:57:31,255 # Creating thread #1, next=2
2020-02-28 17:57:31,257 # Creating thread #2, next=3
2020-02-28 17:57:31,260 # Creating thread #3, next=4
2020-02-28 17:57:31,262 # Creating thread #4, next=0

In master this would fail since there would be some undefined references.

Issues reference

The is the remaining case of tests/periph_rtc that will be dealt with by #13511

[benpicco]

Hm why not do

#ifdef MODULE_TEST_UTILS_INTERACTIVE_SYNC
void test_utils_interactive_sync(void);
#else
static inline void test_utils_interactive_sync(void) {}
#endif

in test_utils/interactive_sync.h instead?

[fjmolinas]

in test_utils/interactive_sync.h instead?

Done.

[dylad]

Tested with the given procedure. Work as expected.
Thanks @fjmolinas, my debugging sessions will be smoother !

[dylad]

Here we go