Fix quoting in non-XSI func_xform, for IRIX sh.

[Ralf Wildenhues]

Another regression from some post-2.2.10 patch I didn't bother to track
down now.  Hopefully fixes all of the 20-some failures I'm seeing on
IRIX ...

Pushed to master.

Cheers,
Ralf

    Fix quoting in non-XSI func_xform, for IRIX sh.
    
    * libltdl/config/ltmain.m4sh (func_xform): Remove spurious extra
    M4 quotes.

diff --git a/libltdl/config/ltmain.m4sh b/libltdl/config/ltmain.m4sh
index f23878e..a1f3b35 100644
--- a/libltdl/config/ltmain.m4sh
+++ b/libltdl/config/ltmain.m4sh
@@ -191,7 +191,7 @@ func_lo2o ()
 # func_xform libobj-or-source
 func_xform ()
 {
-    func_xform_result=`$ECHO "${1}" | $SED 's/\.[[^.]]*$/.lo/'`
+    func_xform_result=`$ECHO "${1}" | $SED 's/\.[^.]*$/.lo/'`
 } # func_xform may be replaced by extended shell implementation