core: enable gnu99 in makefile and reformat slightly
core: enable gnu99 in makefile and reformat slightly

Compile with c99 + gnu extensions and sort definitions in top-level
Makefile.

Signed-off-by: Nico Reißmann <d8255cca0642bdc1e6f9b45da9cb618d308e389b@gmail.com>

phate/jive,phate/jive,phate/jive