trace: Fix user emulator dependency on trace objects

trace: Fix user emulator dependency on trace objects

On a clean build, after generating trace.h, make would recurse into *-*-user
without a clue how to build ../trace.o (added to $(obj-y) in Makefile.target)
since its generation rule is in the main Makefile.
The softmmus are seemingly unaffected because the $(TOOLS), which each have
a dependency on $(trace-obj-y), are built first for the build-all target.

Add a dependency on $(trace-obj-y) for %-user, as done for the qemu-* tools.

Let's be paranoid and do the same for %-softmmu while at it, just in case
someone messes with $(TOOLS) or calls the Makefile target directly.

Signed-off-by: Andreas Färber <[email protected]>
Acked-by: Stefan Weil <[email protected]>
Cc: Stefan Hajnoczi <[email protected]>
Cc: Prerna Saxena <[email protected]>
Cc: Blue Swirl <[email protected]>
Cc: Anthony Liguori <[email protected]>
Signed-off-by: Blue Swirl <[email protected]>