Remove Tempdir from gnatname
The `Tempdir` package is removed from `gnatname` and replaced with `System.OS_Lib`.
The Tempdir package duplicated the Create_Temp_File routine, which is also available in System.OS_Lib. This commit removes the Tempdir package from gnatname and utilizes the System.OS_Lib routine instead. This change eliminates redundancy and simplifies the code.
In Details
This commit modifies gnatname.adb to use the Create_Temp_File routine from System.OS_Lib instead of the one in the Tempdir package. This removes the need for gnatname to depend on Tempdir.
For Context
gnatname is likely a utility for managing Ada source file names. This commit eliminates a redundant function that created temporary files. Now, gnatname uses the standard library function for that purpose. This simplifies the codebase.