testsuite: coverage: Correct value of GCOV_COUNTERS for gcc 14
number of counters have changed in gcc 14 by commit
https://github.com/gcc-mirror/gcc/commit/08a52331803
Specifically, a new counter was added in gcc/gcov-counter.def:
```
/* Conditions. The counter is interpreted as a bit-set. */
DEF_GCOV_COUNTER(GCOV_COUNTER_CONDS, "conditions", _ior)
```
which in turn updates the value of GCOV_COUNTERS that is defined in
gcov-io.h like this:
```
enum {
GCOV_COUNTERS
};
```
Signed-off-by: Roman Studenikin <srv@meta.com>
diff --git a/subsys/testsuite/coverage/coverage.h b/subsys/testsuite/coverage/coverage.h
index 3fd622a..ad180bd 100644
--- a/subsys/testsuite/coverage/coverage.h
+++ b/subsys/testsuite/coverage/coverage.h
@@ -30,7 +30,9 @@
#ifndef _COVERAGE_H_
#define _COVERAGE_H_
-#if (__GNUC__ >= 10)
+#if (__GNUC__ >= 14)
+#define GCOV_COUNTERS 9U
+#elif (__GNUC__ >= 10)
#define GCOV_COUNTERS 8U
#elif (__GNUC__ >= 8)
#define GCOV_COUNTERS 9U
