[PAL] Fix vars initialization issue (flagos-ai#302)

Author: mikethegoblin

flagcx/adaptor/tuner/tuner.cc

@@ -1,11 +1,12 @@
 #include "tuner/tuner_util.h"
 
 #ifdef USE_NVIDIA_ADAPTOR
-std::vector<EnvVar> vars = ncclTunerVars;
+std::vector<EnvVar> &vars = ncclTunerVars;
 #elif USE_METAX_ADAPTOR
-std::vector<EnvVar> vars = mcclTunerVars;
+std::vector<EnvVar> &vars = mcclTunerVars;
 #elif USE_KUNLUNXIN_ADAPTOR
-std::vector<EnvVar> vars = xcclTunerVars;
+std::vector<EnvVar> &vars = xcclTunerVars;
 #else
-std::vector<EnvVar> vars = {};
+std::vector<EnvVar> emptyVars = {};
+std::vector<EnvVar> &vars = emptyVars;
 #endif

flagcx/adaptor/tuner/tuner_util.h

@@ -23,6 +23,6 @@ static void safeStrCopy(char *dst, size_t dstSize, const std::string &src);
 extern std::vector<EnvVar> ncclTunerVars;
 extern std::vector<EnvVar> mcclTunerVars;
 extern std::vector<EnvVar> xcclTunerVars;
-extern std::vector<EnvVar> vars;
+extern std::vector<EnvVar> &vars;
 
 #endif // end include guard