don't have secure_getenv()

Index: thirdparty/openxr/src/common/platform_utils.hpp
--- thirdparty/openxr/src/common/platform_utils.hpp.orig
+++ thirdparty/openxr/src/common/platform_utils.hpp
@@ -94,7 +94,7 @@ static inline char* ImplGetEnv(const char* name) { ret
 // clang-format off
 static inline char* ImplGetSecureEnv(const char* name) {
 #ifdef HAVE_SECURE_GETENV
-    return secure_getenv(name);
+    return getenv(name);
 #elif defined(HAVE___SECURE_GETENV)
     return __secure_getenv(name);
 #else
