[PATCH v1] perf loongarch: Fix discarded const qualifier in _get_field()

[Tiezhu Yang]

When building perf on LoongArch, the following compilation errors occur:

  CC      arch/loongarch/util/header.o
arch/loongarch/util/header.c: In function '_get_field':
arch/loongarch/util/header.c:31:15: error: assignment discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
   31 |         line2 = strrchr(line, ' ');
      |               ^
arch/loongarch/util/header.c:36:12: error: assignment discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
   36 |         nl = strrchr(line, '\n');
      |            ^
cc1: all warnings being treated as errors

Declare 'line2' and 'nl' as const char * to ensure type safety. In modern
glibc versions, strrchr() returns a 'const char *' if the input string is
const.

This is similar to commit 7378b6656aa4 ("perf riscv: Fix discarded const
qualifier in _get_field()").

Fixes: 492ac37fa38f ("perf kvm: Add kvm-stat for loongarch64")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
---
 tools/perf/arch/loongarch/util/header.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/arch/loongarch/util/header.c b/tools/perf/arch/loongarch/util/header.c
index 0c6d823334a2..46f53a74f71e 100644
--- a/tools/perf/arch/loongarch/util/header.c
+++ b/tools/perf/arch/loongarch/util/header.c
@@ -26,7 +26,7 @@
 
 static char *_get_field(const char *line)
 {
-	char *line2, *nl;
+	const char *line2, *nl;
 
 	line2 = strrchr(line, ' ');
 	if (!line2)
-- 
2.42.0