[PATCH i-g-t v2 2/5] tools/intel_reg_spec: Preserve const qualifiers

[Alex Hung <alex.hung@amd.com>]

With glibc 2.43, strrchr() on const input returns a const pointer.
Assigning that result to char * in include_file() discards const
and causes a compiler warning.

The following warning is observed on Ubuntu 26.04 (wrapped):

  ../tools/intel_reg_spec.c: In function 'include_file':
  ../tools/intel_reg_spec.c:242:4: warning:
    assignment discards 'const' qualifier from pointer target type
    [-Wdiscarded-qualifiers]

Use a separate const char * for the source directory separator.
Keep the writable pointer for removing the newline from the
allocated filename.

Assisted-by: Copilot:GPT-6-Astra
Signed-off-by: Alex Hung <alex.hung@amd.com>
---
 tools/intel_reg_spec.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/intel_reg_spec.c b/tools/intel_reg_spec.c
index 632db6b9f..e51c90ec9 100644
--- a/tools/intel_reg_spec.c
+++ b/tools/intel_reg_spec.c
@@ -228,6 +228,7 @@ static bool ignore_line(const char *line)
 
 static char *include_file(const char *line, const char *source)
 {
+	const char *source_dir;
 	char *filename, *p;
 
 	line = skip_space(line);
@@ -239,9 +240,9 @@ static char *include_file(const char *line, const char *source)
 	if (!filename)
 		return NULL;
 
-	p = strrchr(source, '/');
-	if (p && *line != '/') {
-		int len = p - source + 1;
+	source_dir = strrchr(source, '/');
+	if (source_dir && *line != '/') {
+		int len = source_dir - source + 1;
 
 		memcpy(filename, source, len);
 		strcpy(filename + len, line);
-- 
2.53.0