refactor(lsm): allow modules to import other internal header files

lsm/src/_include/lsm/trie_internal.h

@@ -0,0 +1,14 @@
+#ifndef LSM_TRIE_INTERNAL
+#define LSM_TRIE_INTERNAL
+
+#include "lsm/bt_internal.h"
+#include "lsm/str_internal.h"
+#include "lsm/trie.h"
+
+typedef struct lsm_trie_node {
+  lsm_bt bt;
+  lsm_str skip;
+  char c;
+} lsm_trie_node;
+
+#endif

lsm/src/bt/lsm_bt.c

@@ -1,6 +1,6 @@
 #include <stdlib.h>
 
-#include "lsm_bt_internal.h"
+#include "lsm/bt_internal.h"
 
 lsm_error lsm_bt_node_init(lsm_bt_node **ptr, const char key, void *data) {
   lsm_bt_node *node = calloc(1, sizeof(lsm_bt_node));

lsm/src/str/lsm_str.c

@@ -3,7 +3,7 @@
 #include <string.h>
 
 #include "lsm.h"
-#include "lsm_str_internal.h"
+#include "lsm/str_internal.h"
 
 lsm_error lsm_str_init_zero(lsm_str **ptr) {
   lsm_str *str = calloc(1, sizeof(lsm_str));

lsm/src/trie/lsm_trie.c

@@ -0,0 +1 @@
+#include "lsm/trie_internal.h"