[PATCH] libxl: constify some local variables to appease gcc 15.2.1

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

Archlinux just updated gcc to 15.2.1+r604+g0b99615a8aef-1 and that
complains about libxl:

    libxl_cpuid.c: In function ‘libxl_cpuid_parse_config_xend’:
    libxl_cpuid.c:447:16: error: assignment discards ‘const’ qualifier from 
pointer target type [-Werror=discarded-qualifiers]
      447 |         endptr = strchr(str, '=');
          |                ^
    libxl_cpuid.c:452:16: error: assignment discards ‘const’ qualifier from 
pointer target type [-Werror=discarded-qualifiers]
      452 |         endptr = strchr(str, ',');
          |                ^
    libxl_cpuid.c:454:20: error: assignment discards ‘const’ qualifier from 
pointer target type [-Werror=discarded-qualifiers]
      454 |             endptr = strchr(str, 0);
          |                    ^
    libxl_cpuid.c: In function ‘libxl_cpuid_parse_config_xend’:
    libxl_cpuid.c:447:16: error: assignment discards ‘const’ qualifier from 
pointer target type [-Werror=discarded-qualifiers]
      447 |         endptr = strchr(str, '=');
          |                ^
    libxl_cpuid.c:452:16: error: assignment discards ‘const’ qualifier from 
pointer target type [-Werror=discarded-qualifiers]
      452 |         endptr = strchr(str, ',');
          |                ^
    libxl_cpuid.c:454:20: error: assignment discards ‘const’ qualifier from 
pointer target type [-Werror=discarded-qualifiers]
      454 |             endptr = strchr(str, 0);
          |                    ^
    cc1: all warnings being treated as errors

Add missing consts. Note in libxl_cpuid_parse_config_xend() non-const
endptr still is needed, to be compatible with the second argument to
strtoul(). Add second variable for this reason.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
When I say "just updated" I really mean it. The update hit me between my
CI saying "ok" and release build few hours later. I guess Xen's CI will
see that only after next refresh of the Arch container (next week?).
---
 tools/libs/light/libxl_cpuid.c    | 19 ++++++++++---------
 tools/libs/light/libxl_internal.c |  2 +-
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/tools/libs/light/libxl_cpuid.c b/tools/libs/light/libxl_cpuid.c
index 8420b2465f39..5fb580113d80 100644
--- a/tools/libs/light/libxl_cpuid.c
+++ b/tools/libs/light/libxl_cpuid.c
@@ -415,6 +415,7 @@ int libxl_cpuid_parse_config_xend(libxl_cpuid_policy_list 
*policy,
                                   const char* str)
 {
     char *endptr;
+    const char *endptrc;
     unsigned long value;
     uint32_t leaf, subleaf = XEN_CPUID_INPUT_UNUSED;
     struct xc_xend_cpuid *entry;
@@ -444,25 +445,25 @@ int libxl_cpuid_parse_config_xend(libxl_cpuid_policy_list 
*policy,
             return 4;
         }
         value = str[1] - 'a';
-        endptr = strchr(str, '=');
-        if (value > 3 || endptr == NULL) {
+        endptrc = strchr(str, '=');
+        if (value > 3 || endptrc == NULL) {
             return 4;
         }
-        str = endptr + 1;
-        endptr = strchr(str, ',');
-        if (endptr == NULL) {
-            endptr = strchr(str, 0);
+        str = endptrc + 1;
+        endptrc = strchr(str, ',');
+        if (endptrc == NULL) {
+            endptrc = strchr(str, 0);
         }
-        if (endptr - str != 32) {
+        if (endptrc - str != 32) {
             return 5;
         }
         entry->policy[value] = calloc(32 + 1, 1);
         strncpy(entry->policy[value], str, 32);
         entry->policy[value][32] = 0;
-        if (*endptr == 0) {
+        if (*endptrc == 0) {
             break;
         }
-        for (str = endptr + 1; *str == ' ' || *str == '\n'; str++);
+        for (str = endptrc + 1; *str == ' ' || *str == '\n'; str++);
     }
     return 0;
 }
diff --git a/tools/libs/light/libxl_internal.c 
b/tools/libs/light/libxl_internal.c
index 2941ca0bbd0e..d70cfed7d88f 100644
--- a/tools/libs/light/libxl_internal.c
+++ b/tools/libs/light/libxl_internal.c
@@ -204,7 +204,7 @@ char *libxl__strndup(libxl__gc *gc, const char *c, size_t n)
 
 char *libxl__dirname(libxl__gc *gc, const char *s)
 {
-    char *c = strrchr(s, '/');
+    const char *c = strrchr(s, '/');
 
     if (!c)
         return NULL;
-- 
2.51.0