c: move c files into nostrdb in prep for switchover

nostrdb/varint.h

@@ -0,0 +1,14 @@
+
+#ifndef PROTOVERSE_VARINT_H
+#define PROTOVERSE_VARINT_H
+
+#define VARINT_MAX_LEN 9
+
+#include <stddef.h>
+#include <stdint.h>
+
+size_t varint_put(unsigned char buf[VARINT_MAX_LEN], uint64_t v);
+size_t varint_size(uint64_t v);
+size_t varint_get(const unsigned char *p, size_t max, int64_t *val);
+
+#endif /* PROTOVERSE_VARINT_H */