Work around a bug in file-inclusion mechanism of Solaris make.
* automake.in (handle_single_transform): In the name of the
dependency file: collapse multiple slash characters into a single
one.
* tests/subobj11a.test: New test.
* tests/subobj11b.test: Likewise.
* tests/subobj11c.test: Likewise.
* tests/depcomp8a.test: Likewise.
* tests/depcomp8b.test: Likewise.
* tests/Makefile.am (TESTS): Updated.
* NEWS: Updated.
Report by Stefano Lattarini, quick fix by Ralf Wildenhues, final
patch and tests by Stefano Lattarini.