ptest-runner2: Explicitly set EXTRA_OEMAKE as required

This recipe currently relies on EXTRA_OEMAKE having been set to "-e MAKEFLAGS=" in bitbake.conf to operate. It is necessary to make this explicit so that the default in bitbake.conf can be change

index 97c640c..8f9a170 100644
@@ -15,6 +15,8 @@ FILES_${PN} = "${bindir}/ptest-runner"
 
 RCONFLICTS_${PN} = "ptest-runner"
 
+EXTRA_OEMAKE = "-e MAKEFLAGS="
+
 do_compile () {
 	oe_runmake
 }

Sorry, ignore this one as it was caused my stale changes in a local branch.

Cheers,

Richard