rpm: Add workaround for debugedit-segv

[ YOCTO #4089 ]

On PPC and MIPS, there appears to be a condition that causes
debugedit to segfault.  The segfault is related to a call into
the md5hash algorithm, an address of '0', and a size > 0 is passed
causing the access of the address to segv.

This workaround may prove to be the final fix, but it's currently
unclear what the actual cause of the 0 address is.

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
gnupg: Add symlink for gpgv

Gnupg 2.0.19 installs 'gpgv2' but apt-get and possibly other utilities expect
to find this as 'gpgv'. A symlink is created in the same way as the link for
'gpg'.

Signed-off-by: Paul Barker <paul@paulbarker.me.uk>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
package.bbclass: Handle subprocess errors correctly

If an error occurs in subprocess.call() we currently don't catch it. In particular
we have issues where debugedit is segfaulting unnoticed. This fixes up
various code paths to catch the errors.

[YOCTO #4089]

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
conf/machine: Clean up MACHINEOVERRIDES handling

OVERRIDES reads from left to right, least to most specific. We were
appending to MACHINEOVERRIDES when we should have been prepending so
the ordering of qemuall verses qemuxxx was incorrect, as was the x86
override and several of the arm overrides. This patch is a batch cleanup
of the various issues to correct the order from least to most specific.
The include order does matter and we needed to tweak some of that in this
patch too.

[YOCTO #4090]

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
package.bbclass: Ensure debug source file is generated correctly

The command for generating debug sources appends to the file, therefore we need
to ensure it does not exist before we run the command else we end up doing
more work that we should have to.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>