yanglint FEATURE --yang-library-file for inter-mod

Data file to create an exact YANG schema context is now available
in the interactive mode.
diff --git a/tools/lint/common.c b/tools/lint/common.c
index f2ff464..96fdb76 100644
--- a/tools/lint/common.c
+++ b/tools/lint/common.c
@@ -954,3 +954,26 @@
     *ext_data_free = 1;
     return LY_SUCCESS;
 }
+
+LY_ERR
+searchpath_strcat(char **searchpaths, const char *path)
+{
+    uint64_t len;
+    char *new;
+
+    if (!(*searchpaths)) {
+        *searchpaths = strdup(path);
+        return LY_SUCCESS;
+    }
+
+    len = strlen(*searchpaths) + strlen(path) + strlen(PATH_SEPARATOR);
+    new = realloc(*searchpaths, sizeof(char) * len + 1);
+    if (!new) {
+        return LY_EMEM;
+    }
+    strcat(new, PATH_SEPARATOR);
+    strcat(new, path);
+    *searchpaths = new;
+
+    return LY_SUCCESS;
+}