Target all should create all necessary files in topdir. Currently
they're only needed for static file checks, but they might well be
prerequistes for the build to succeed in the future, so make target
all depend on topdir.
Also, place target all before the block of includes, so that the
execution order is defined in topdir.mk rather than the included
snippets.
Signed-off-by: Jan Lindemann <jan@janware.com>