Does not compile on OSX

[brainstorm]

Feeling lazy for a PR with the proper ifdefs, but you get the idea:

$ git diff
diff --git a/binbloom.c b/binbloom.c
index 171765c..6a6f31b 100644
--- a/binbloom.c
+++ b/binbloom.c
@@ -18,7 +18,7 @@
 #include <stdlib.h>
 #include <stdint.h>
 #include <string.h>
-#include <malloc.h>
+#include <malloc/malloc.h>
 #include <assert.h>
 #include <unistd.h>
 #include <sys/types.h>

Otherwise:

$ make
gcc -O3 -Wall -Wextra binbloom.c -o binbloom
binbloom.c:21:10: fatal error: 'malloc.h' file not found
#include <malloc.h>
         ^~~~~~~~~~
1 error generated.
make: *** [binbloom] Error 1