The 'build.mk' file checks if the tool chain to be used supports the
'-static' and '-fno-stack-protector' flags, but this check always fails
for the current Genode tool chain because it cannot create executable
files without explicitly specifying the 'crt0' and library files to be
linked, which the check doesn't.
This patch removes the compiler check.
Fixes#358.
The build system overlays multiple source trees (repositories) such that
they can shadow libraries and include search paths. This patch extends
the shadowing concept to build targets. Furthermore, it streamlines the
build stage for generating library depenencies, reducing the processing
time of this stage by 10-20 percent. Fixes#165.