[RESEND PATCH v2] kallsyms: fix build without execinfo

[Achill Gilgenast]

Some libc's like musl libc don't provide execinfo.h since it's not part
of POSIX. In order to fix compilation on musl, only include execinfo.h
if available (HAVE_BACKTRACE_SUPPORT)

This was discovered with c104c16073b7 ("Kunit to check the longest symbol length")
which starts to include linux/kallsyms.h with Alpine Linux' configs.

Signed-off-by: Achill Gilgenast <fossdd@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 tools/include/linux/kallsyms.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/include/linux/kallsyms.h b/tools/include/linux/kallsyms.h
index 5a37ccbec54f..f61a01dd7eb7 100644
--- a/tools/include/linux/kallsyms.h
+++ b/tools/include/linux/kallsyms.h
@@ -18,6 +18,7 @@ static inline const char *kallsyms_lookup(unsigned long addr,
 	return NULL;
 }
 
+#ifdef HAVE_BACKTRACE_SUPPORT
 #include <execinfo.h>
 #include <stdlib.h>
 static inline void print_ip_sym(const char *loglvl, unsigned long ip)
@@ -30,5 +31,8 @@ static inline void print_ip_sym(const char *loglvl, unsigned long ip)
 
 	free(name);
 }
+#else
+static inline void print_ip_sym(const char *loglvl, unsigned long ip) {}
+#endif
 
 #endif
-- 
2.50.0