Fix path to post-processing merge script (#187)

- Path to merge script not found unless user explicitly sources "share/rocprofiler-systems/setup-env.sh" to setup PATHs.
- Instead, let's derive the path when the application loads and use it when executing the helper script
- Rename script to rocprof-sys-merge-output.sh.
- Change install folder to <prefix>/libexec/rocprofiler-systems based on dev-ops feedback.
- Updated PATH variable in the modulefile and source scrtipt.
- For SWDEV-528101

source/bin/rocprof-sys-causal/impl.cpp

@@ -246,6 +246,7 @@ prepare_environment_for_run(std::vector<char*>& _env)
                    join(":", LIBPTHREAD_SO,
                         get_realpath(get_internal_libpath("librocprof-sys-dl.so"))),
                    true);
+        update_env(_env, "ROCPROFSYS_SCRIPT_DIR", get_internal_script_path());
     }
 }
 
@@ -259,6 +260,20 @@ get_internal_libpath(const std::string& _lib)
     return rocprofsys::common::join("/", _dir, "..", "lib", _lib);
 }
 
+std::string
+get_internal_script_path(void)
+{
+    auto _exe = std::string_view{ realpath("/proc/self/exe", nullptr) };
+    auto _pos = _exe.find_last_of('/');
+    auto _dir = std::string{ "./" };
+    if(_pos != std::string_view::npos) _dir = _exe.substr(0, _pos);
+
+    auto _script_dir = get_realpath(
+        rocprofsys::common::join("/", _dir, "..", "libexec", "rocprofiler-systems"));
+
+    return _script_dir;
+}
+
 void
 print_updated_environment(std::vector<char*> _env, std::string_view _prefix)
 {