Fix warning ``warning: function declaration isn’t a prototype`` when building mimalloc with ``-Wstrict-prototypes`` flag. In C argumentless functions should be declared as ``func(void)``. Reproducer: ```shell $ cmake ../.. -DCMAKE_C_FLAGS="-Wstrict-prototypes" $ make VERBOSE=1 ``` Co-authored-by: Sam Gross <colesbury@gmail.com> Co-authored-by: Neil Schemenauer <nas@arctrix.com> Signed-off-by: Christian Heimes <christian@python.org>