gcov: support GCC 7.1

Starting from GCC 7.1, __gcov_exit is a new symbol expected to be
implemented in a profiling runtime.

[[e-mail]: coding-style fixes]
[[e-mail]: v2]
Link: http://lkml.kernel.org/r/[e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Martin Liska <[e-mail]>
Acked-by: Peter Oberparleiter <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/gcov/base.c

···
 }
 EXPORT_SYMBOL(__gcov_merge_icall_topn);
 
+void __gcov_exit(void)
+{
+	/* Unused. */
+}
+EXPORT_SYMBOL(__gcov_exit);
+
 /**
  * gcov_enable_events - enable event reporting through gcov_event()
  *

kernel/gcov/gcc_4_7.c

···
 #include <linux/vmalloc.h>
 #include "gcov.h"
 
-#if (__GNUC__ > 5) || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1)
+#if (__GNUC__ >= 7)
+#define GCOV_COUNTERS			9
+#elif (__GNUC__ > 5) || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1)
 #define GCOV_COUNTERS			10
 #elif __GNUC__ == 4 && __GNUC_MINOR__ >= 9
 #define GCOV_COUNTERS			9