add SLOB allocator

src/sloballoc.h

@@ -0,0 +1,15 @@
+#ifndef SLOBALLOC_H_SEEN
+#define SLOBALLOC_H_SEEN
+
+#include <stddef.h>
+
+typedef struct slob SLOB;
+
+SLOB *slobinit(void *mem, size_t size);
+void *sloballoc(SLOB *slob, size_t size);
+void slobfree(SLOB *slob, void *p);
+
+// consistency check (verify internal invariants); returns 0 on success
+int slobcheck(SLOB *slob);
+
+#endif // SLOBALLOC_H_SEEN