nostrdb: move everything to src

Signed-off-by: William Casarin <jb55@jb55.com>

nostrdb/src/util.h

@@ -0,0 +1,33 @@
+
+#ifndef NDB_UTIL_H
+#define NDB_UTIL_H
+
+static inline int min(int a, int b) {
+    return a < b ? a : b;
+}
+
+static inline int max(int a, int b) {
+    return a > b ? a : b;
+}
+
+static inline void* memdup(const void* src, size_t size) {
+	void* dest = malloc(size);
+	if (dest == NULL) {
+		return NULL;  // Memory allocation failed
+	}
+	memcpy(dest, src, size);
+	return dest;
+}
+
+static inline char *strdupn(const char *src, size_t size) {
+	char* dest = malloc(size+1);
+	if (dest == NULL) {
+		return NULL;  // Memory allocation failed
+	}
+	memcpy(dest, src, size);
+	dest[size] = '\0';
+	return dest;
+}
+
+#endif // NDB_UTIL_H
+