introduce compileTest function

this cuts down the enormous duplication of identical command line args
passed to compile.test.
this necessitates the addition of a -config parameter to compile.test,
as QMAKE_CONFIG needs to be extended in some cases.

Change-Id: I677b2fea4a407b9e4395e70a25e4e349efb0a946
Reviewed-by: Joerg Bornemann <joerg.bornemann@nokia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>