qemu: Limit paths searched during user mode emulation
By default qemu builds a complete list of directories within the user
emulation sysroot (-L option). The OE sysroot directory is large and
this is confusing, for example it indexes all pkgdata. In particular this
confuses strace of qemu binaries with tons of irrelevant paths.
This patch stops the code indexing up front and instead only indexes
things if/as/when it needs to. This drastically reduces the files it
reads and reduces memory usage and cleans up strace.
It would also avoid the infinite directory traversal bug in [YOCTO #6996]
although the code could still be vulnerable if it parsed those specific
paths.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
