Remove unneeded variable for GetLastError();

No other usage of GetLastError has the result assigned to a variable first in this code, so it is better if we make check_user_is_admin the same in that regard.

src/common/common.cpp

@@ -479,7 +479,7 @@ bool check_user_is_admin()
     };
 
     HANDLE hToken;
-    DWORD dwSize = 0, dwResult = 0;
+    DWORD dwSize = 0;
     PTOKEN_GROUPS pGroupInfo;
     SID_IDENTIFIER_AUTHORITY SIDAuth = SECURITY_NT_AUTHORITY;
     PSID pSID = NULL;
@@ -493,8 +493,7 @@ bool check_user_is_admin()
     // Call GetTokenInformation to get the buffer size.
     if (!GetTokenInformation(hToken, TokenGroups, NULL, dwSize, &dwSize))
     {
-        dwResult = GetLastError();
-        if (dwResult != ERROR_INSUFFICIENT_BUFFER)
+        if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
         {
             return true;
         }
@@ -636,4 +635,4 @@ std::optional<std::string> exec_and_read_output(const std::wstring_view command,
 exit:
     CancelIo(readPipe.get());
     return childOutput;
-}
+}