Add optllvm as allowed way in testsuite

The hooks for the optllvm way were there in the ghc config
file, but there was no entry in config.other_ways so that a
`make WAY=optllvm` would fail with an "unknown way" error
message.

This patch simply adds optllvm to the other_ways list.

testsuite/config/ghc

@@ -26,7 +26,7 @@ config.other_ways         = ['extcore','optextcore',
                              'prof_hc_hb','prof_hb',
                              'prof_hd','prof_hy','prof_hr',
                              'threaded1_ls', 'threaded2_hT',
-                             'llvm', 'debugllvm']
+                             'llvm', 'debugllvm', 'optllvm']
 
 if (ghc_with_native_codegen == 1):
     config.compile_ways.append('optasm')