Make transformer_engine::getenv arguments independent of C++ ABI version (#896)

Make transformer_engine::getenv independent of C++ ABI version
Signed-off-by: Kirthi Shankar Sivamani <ksivamani@nvidia.com>

transformer_engine/common/util/cuda_runtime.cpp

@@ -98,7 +98,7 @@ const std::string &include_directory(bool required) {
       {"", "/usr/local/cuda"}};
     for (auto &[env, p] : search_paths) {
       if (p.empty()) {
-        p = getenv<Path>(env);
+        p = getenv<Path>(env.c_str());
       }
       if (!p.empty()) {
         if (file_exists(p / "cuda_runtime.h")) {

transformer_engine/common/util/system.cpp

@@ -20,9 +20,9 @@ namespace {
 
 template <typename T>
 inline typename std::enable_if<std::is_arithmetic<T>::value, T>::type
-getenv_helper(const std::string &variable, const T &default_value) {
+getenv_helper(const char *variable, const T &default_value) {
   // Implementation for numeric types
-  const char *env = std::getenv(variable.c_str());
+  const char *env = std::getenv(variable);
   if (env == nullptr || env[0] == '\0') {
     return default_value;
   }
@@ -35,9 +35,9 @@ getenv_helper(const std::string &variable, const T &default_value) {
 
 template <typename T>
 inline typename std::enable_if<!std::is_arithmetic<T>::value, T>::type
-getenv_helper(const std::string &variable, const T &default_value) {
+getenv_helper(const char *variable, const T &default_value) {
   // Implementation for string-like types
-  const char *env = std::getenv(variable.c_str());
+  const char *env = std::getenv(variable);
   if (env == nullptr || env[0] == '\0') {
     return default_value;
   } else {
@@ -48,11 +48,11 @@ getenv_helper(const std::string &variable, const T &default_value) {
 }  // namespace
 
 #define NVTE_INSTANTIATE_GETENV(T, default_value)          \
-  template <> T getenv<T>(const std::string &variable,          \
+  template <> T getenv<T>(const char *variable,            \
                           const T &default_value_) {       \
     return getenv_helper<T>(variable, default_value_);     \
   }                                                        \
-  template <> T getenv<T>(const std::string &variable) {        \
+  template <> T getenv<T>(const char *variable) {          \
     return getenv_helper<T>(variable, default_value);      \
   }
 NVTE_INSTANTIATE_GETENV(bool, false);

transformer_engine/common/util/system.h

@@ -19,11 +19,11 @@ namespace transformer_engine {
  * returned.
  */
 template <typename T = std::string>
-T getenv(const std::string &variable);
+T getenv(const char *variable);
 
 /*! \brief Get environment variable and convert to type */
 template <typename T = std::string>
-T getenv(const std::string &variable, const T &default_value);
+T getenv(const char *variable, const T &default_value);
 
 /*! \brief Check if a file exists and can be read */
 bool file_exists(const std::string &path);