bug#79826: add parentheses in ltmain.in to support values with spaces

"Richard J. Mathar" <[email protected]> Thu, 13 Nov 2025 10:09:40 +0100
Newsgroups gmane.comp.gnu.libtool.bugs
Message-ID <[email protected]>
In line 9475 of libtool/build-aux/ltmain.in quotes are missing around the variable in the else branch. 
It should be
    cd "$darwin_orig_dir"
the same as two lines earlier. Reason: The variable may contain a value with spaces that 
cause errors due to the standard splitting of command line arguments by linux shells.
See https://github.com/autotools-mirror/libtool/pull/4/files .