libyang CHANGE headers includes cleanup using include-what-you-use tool (#1098)

diff --git a/src/tree_schema_internal.h b/src/tree_schema_internal.h
index 5d10992..ee5b870 100644
--- a/src/tree_schema_internal.h
+++ b/src/tree_schema_internal.h
@@ -17,7 +17,7 @@
 
 #include <stdint.h>
 
-#include "plugins_exts.h"
+#include "common.h"
 #include "set.h"
 #include "tree_schema.h"
 #include "xml.h"
@@ -163,6 +163,26 @@
 };
 
 /**
+ * @brief internal context for compilation
+ */
+struct lysc_ctx {
+    struct ly_ctx *ctx;
+    struct lys_module *mod;
+    struct lys_module *mod_def; /**< context module for the definitions of the nodes being currently
+                                     processed - groupings are supposed to be evaluated in place where
+                                     defined, but its content instances are supposed to be placed into
+                                     the target module (mod) */
+    struct ly_set groupings;    /**< stack for groupings circular check */
+    struct ly_set unres;        /**< to validate leafref's target and xpath of when/must */
+    struct ly_set dflts;        /**< set of incomplete default values */
+    struct ly_set tpdf_chain;
+    uint16_t path_len;
+    int options;                /**< various @ref scflags. */
+#define LYSC_CTX_BUFSIZE 4078
+    char path[LYSC_CTX_BUFSIZE];
+};
+
+/**
  * @brief Check that \p c is valid UTF8 code point for YANG string.
  *
  * @param[in] ctx parser context for logging.