update(docker,falco_scripts): fix kernel module build on Flatcar

Relocate necessary tools from the kernel module build system to run using host
dynlinker and libraries, so that compiling falco module on Flatcar works.

Since Flatcar v2983.0.0, Flatcar ships with glibc-2.33, but the
falco-driver-loader container is based on debian:buster and so has a much older
glibc. This prevents some necessary tools within /lib/modules/*/build from
working which causes the falco module to fail to compile using dkms.

To make the tools work, we need to relocate them so we add patchelf to the
falco and local dockerfiles. The relocation is based on the approach done by
the sysdig agent-kmodule build system, but I'm unable to find the source code
for it. The host linker and libs will be found at /host/usr/lib64, so we change
the interpreter and rpath on the tools. The relocation happens on a copy of the
tools which are then bind mounted at the right location. The result allows the
module build to work.

Signed-off-by: Jeremi Piotrowski <jpiotrowski@microsoft.com>

docker/falco/Dockerfile

@@ -34,6 +34,7 @@ RUN apt-get update \
 	libssl-dev \
 	llvm-7 \
 	netcat \
+	patchelf \
 	xz-utils \
 	&& rm -rf /var/lib/apt/lists/*
 

docker/local/Dockerfile

@@ -40,6 +40,7 @@ RUN apt-get update \
 	liblsan0 \
 	libtsan0 \
 	libcc1-0 \
+	patchelf \
 	&& rm -rf /var/lib/apt/lists/*
 
 RUN if [ "$TARGETARCH" = "amd64" ]; \