providers.py: enhance the runtime debug degbug messgae

The runtime provider debug message is the same as the build time debug
message, make them different would be better.

[YOCTO #5067]

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
runqueue.py: check whether multiple versions of the same PN are due to be built

There would be an race issue if we:

$ bitbake make-3.81 make-3.82

This because they are being built at the same time which would cause
unexpected problems, for example:

[snip]
ERROR: Package already staged (/path/to/tmp/sstate-control/manifest-qemux86-make.populate-sysroot)?!
ERROR: Function failed: sstate_task_postfunc
[snip]

Or there would be python's strack trace such as:

[snip]
 *** 0004:    mfile = open(manifest)
     0005:    entries = mfile.readlines()
     0006:    mfile.close()
     0007:
     0008:    for entry in entries:
Exception: IOError: [Errno 2] No such file or directory: xxx
[snip]

[YOCTO #5094]

We can quit earlier to avoid this kind of issue when two versions of the same PN
are going to be built since this isn't supported.

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>