Fix KDE3 .la file format on Cygwin

We teach KDE3Macros.cmake to generate .la files on Cygwin that match
those produced by libtool.  See issue #10122.

Modules/KDE3Macros.cmake

@@ -322,7 +322,11 @@ MACRO(KDE3_INSTALL_LIBTOOL_FILE _target)
    FILE(APPEND ${_laname} "# The name that we can dlopen(3).\n")
    FILE(APPEND ${_laname} "dlname='${_soname}'\n")
    FILE(APPEND ${_laname} "# Names of this library\n")
-   FILE(APPEND ${_laname} "library_names='${_soname} ${_soname} ${_soname}'\n")
+   IF(CYGWIN)
+     FILE(APPEND ${_laname} "library_names='${_soname}'\n")
+   ELSE(CYGWIN)
+     FILE(APPEND ${_laname} "library_names='${_soname} ${_soname} ${_soname}'\n")
+   ENDIF(CYGWIN)
    FILE(APPEND ${_laname} "# The name of the static archive\n")
    FILE(APPEND ${_laname} "old_library=''\n")
    FILE(APPEND ${_laname} "# Libraries that this one depends upon.\n")