We use dwarfsrcfiles in package.bbclass to list the source files used by a binary.
This is done before they're stripped and linked to debug symbols in separate files.
It is possible a binary may already have a link to separate debug symbols, e.g.
some of the test binaries in lttng-tools ptest. In those cases, the linked binary
may be changed by package.bbclass code whilst dwarfsrcfiles is reading it. That
would result in a rare SIGBUS race causing the binary to fail.
To avoid this, break the debug file search path so no other binaries are found.
Also fix a segfault if no binary is specified while here.
[YOCTO #14400]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
