This reverts commit 208ecb3e1acc8d55dab49fdf721a86d513691688. This was
causing problems by making DEF_TARGET_LIST pointless and having to
jump through hoops to build on mingw with a dully enabled config.
This includes a change to fix the per-guest TCG test probe which was
added after 208ecb3 and used TARGET_LIST.
Backports commit 2b1f35b9a85cf0232615a67e7ff523137a58795e from qemu
To be more accurate on its purpose and make code that looks for a certain
target out of this variable more readable.
Backports commit 208ecb3e1acc8d55dab49fdf721a86d513691688 from qemu
