AP_HAL_SITL: simplify lookup_location using null-terminated data

libraries/AP_HAL_SITL/SITL_cmdline.cpp

@@ -701,29 +701,22 @@ bool SITL_State::parse_home(const char *home_str, Location &loc, float &yaw_degr
 bool SITL_State::lookup_location(const char *home_str, Location &loc, float &yaw_degrees)
 {
     const char *locations = "@ROMFS/locations.txt";
-    FileData *fd = AP::FS().load_file(locations);
+    FileData *fd = AP::FS().load_file(locations); // data is null-terminated
     if (fd == nullptr) {
         ::printf("Missing %s\n", locations);
         return false;
     }
-    char *str = strndup((const char *)fd->data, fd->length);
-    if (!str) {
-        delete fd;
-        return false;
-    }
     size_t len = strlen(home_str);
     char *saveptr = nullptr;
-    for (char *s = strtok_r(str, "\r\n", &saveptr);
+    for (char *s = strtok_r((const char*)fd->data, "\r\n", &saveptr);
          s;
          s=strtok_r(nullptr, "\r\n", &saveptr)) {
         if (strncasecmp(s, home_str, len) == 0 && s[len]=='=') {
             bool ok = parse_home(&s[len+1], loc, yaw_degrees);
-            free(str);
             delete fd;
             return ok;
         }
     }
-    free(str);
     delete fd;
     ::printf("Failed to find location '%s'\n", home_str);
     return false;