Pass the destination buffer size minus one to strncpy

Copying the last byte was pointless, since the next line overwrites it,
and resulted in a compiler warning:

../src/intel/common/intel_measure.c: In function 'intel_measure_init':
../src/intel/common/intel_measure.c:68:7: warning: 'strncpy' specified bound 1024 equals destination size [-Wstringop-truncation]
   68 |       strncpy(env_copy, env, 1024);
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

This allows dropping -Wno-error=stringop-truncation from the
debian-x86_64-asan & debian-{arm64,x86_64}-ubsan CI jobs.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39429>

.gitlab-ci/build/gitlab-ci.yml

@@ -60,7 +60,6 @@ debian-x86_64-asan:
     VULKAN_DRIVERS: "swrast,amd,intel"
     GALLIUM_DRIVERS: "llvmpipe,softpipe,zink,r300"
     C_ARGS: >
-      -Wno-error=stringop-truncation
       -Wno-error=deprecated-declarations
     EXTRA_OPTION: >
       -D intel-elk=false
@@ -149,7 +148,6 @@ debian-x86_64-ubsan:
   variables:
     C_ARGS: >
       -Wno-error=stringop-overflow
-      -Wno-error=stringop-truncation
       -Wno-error=deprecated-declarations
     CPP_ARGS: >
       -Wno-error=array-bounds
@@ -533,7 +531,6 @@ debian-arm64-ubsan:
     C_ARGS: >
       -Wno-error=array-bounds
       -Wno-error=stringop-overflow
-      -Wno-error=stringop-truncation
       -Wno-error=deprecated-declarations
     CPP_ARGS: >
       -Wno-error=array-bounds

src/gallium/auxiliary/hud/hud_driver_query.c

@@ -383,7 +383,7 @@ hud_pipe_query_install(struct hud_batch_query_context **pbq,
    if (!gr)
       return;
 
-   strncpy(gr->name, name, sizeof(gr->name));
+   strncpy(gr->name, name, sizeof(gr->name) - 1);
    gr->name[sizeof(gr->name) - 1] = '\0';
    gr->query_data = CALLOC_STRUCT(query_info);
    if (!gr->query_data)

src/intel/common/intel_measure.c

@@ -65,7 +65,7 @@ intel_measure_init(struct intel_measure_device *device)
          return;
 
       char env_copy[1024];
-      strncpy(env_copy, env, 1024);
+      strncpy(env_copy, env, 1023);
       env_copy[1023] = '\0';
 
       config.file = stderr;