env: Create a new file for environment functions

At present we have environment.h but this file includes all the
environment-related header files as well as internals such as
default_environment.

It seems desirable to have a new header to hold the commonly used
environment functions, so that most files can avoid including all of this
unnecessary stuff.

Create a new env.h header and move one function over to it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>

include/env.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Common environment functions
+ *
+ * (C) Copyright 2000-2009
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ */
+
+#ifndef __ENV_H
+#define __ENV_H
+
+#include <stdbool.h>
+
+/**
+ * env_complete() - return an auto-complete for environment variables
+ *
+ * @var: partial name to auto-complete
+ * @maxv: Maximum number of matches to return
+ * @cmdv: Returns a list of possible matches
+ * @maxsz: Size of buffer to use for matches
+ * @buf: Buffer to use for matches
+ * @dollar_comp: non-zero to wrap each match in ${...}
+ * @return number of matches found (in @cmdv)
+ */
+int env_complete(char *var, int maxv, char *cmdv[], int maxsz, char *buf,
+		 bool dollar_comp);
+
+#endif