testsuite: convert some `suffix*' tests to TAP

testsuite: convert some `suffix*' tests to TAP

This will allow us to explicitly declare some expected failures
involving Solaris make as such, instead of partly papering over
them with skips and partly letting them fail too loudly.

* tests/suffix-chain.test: Rename ...
* tests/suffix-chain.tap: ... to this, and convert to the use of
TAP.  Also, fix some bugs since we are at it, and ...
($required): ... require `cc'.
* tests/suffix3.test: Rename ...
* tests/suffix3.tap: ... to this, and convert to the use of TAP.
Also, since we are at it, throw in some formatting fixes.
* tests/suffix8.test: Rename ...
* tests/suffix8.tap: ... to this, and convert to the use of TAP.
Also, since we are at it, throw in some formatting fixes.
* tests/suffix10.test: Rename ...
* tests/suffix10.tap: ... to this, and convert to the use of TAP.
* tests/suffix11.test: Rename ...
* tests/suffix11.tap: ... to this, and convert to the use of TAP.
* tests/Makefile.am (TESTS): Update.