build: fix section-renaming of libfdt and libelf

build: fix section-renaming of libfdt and libelf

In common/libelf/Makefile, when SECTIONS gets defined
SPECIAL_DATA_SECTIONS doesn't exist, so only "text data" sections are
been renamed. This was different before 48115d14743e ("Move more
kernel decompression bits to .init.* sections"). By introducing the
same renaming mechanism the to libfdt (9ba1f198f61e ["xen/libfdt: Put
all libfdt in init"]), the issue was extended to there as well.

Move SPECIAL_DATA_SECTIONS in Rules.mk before including "Makefile" to
fix this.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>