gcov: add support for GCC 15

Using gcov on kernels compiled with GCC 15 results in truncated 16-byte
long .gcda files with no usable data.  To fix this, update GCOV_COUNTERS
to match the value defined by GCC 15.

Tested with GCC 14.3.0 and GCC 15.2.0.

Link: https://lkml.kernel.org/r/20251028115125.1319410-1-oberpar@linux.ibm.com
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reported-by: Matthieu Baerts <matttbe@kernel.org>
Closes: linux-test-project/lcov#445
Tested-by: Matthieu Baerts <matttbe@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: oberpar

kernel/gcov/gcc_4_7.c

@@ -18,7 +18,9 @@
 #include <linux/mm.h>
 #include "gcov.h"
 
-#if (__GNUC__ >= 14)
+#if (__GNUC__ >= 15)
+#define GCOV_COUNTERS			10
+#elif (__GNUC__ >= 14)
 #define GCOV_COUNTERS			9
 #elif (__GNUC__ >= 10)
 #define GCOV_COUNTERS			8