libc: Add opterr global variable

defined here:
https://pubs.opengroup.org/onlinepubs/9699919799/functions/getopt.html

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>

include/unistd.h

@@ -296,10 +296,12 @@ extern "C"
 
 #ifndef __NXFLAT__
 EXTERN FAR char *optarg; /* Optional argument following option */
+EXTERN int       opterr; /* Print error message */
 EXTERN int       optind; /* Index into argv */
 EXTERN int       optopt; /* Unrecognized option character */
 #else
 #  define optarg  (*(getoptargp()))
+#  define opterr  (*(getopterrp()))
 #  define optind  (*(getoptindp()))
 #  define optopt  (*(getoptoptp()))
 #endif
@@ -389,6 +391,7 @@ int     getopt(int argc, FAR char * const argv[], FAR const char *optstring);
  */
 
 FAR char **getoptargp(void);  /* Optional argument following option */
+FAR int   *getopterrp(void);  /* Print error message */
 FAR int   *getoptindp(void);  /* Index into argv */
 FAR int   *getoptoptp(void);  /* Unrecognized option character */
 

libs/libc/libc.csv

@@ -55,6 +55,7 @@
 "gethostname","unistd.h","","int","FAR char *","size_t"
 "getopt","unistd.h","","int","int","FAR char * const []|FAR char * const *","FAR const char *"
 "getoptargp","unistd.h","","FAR char **"
+"getopterrp","unistd.h","","FAR int *"
 "getoptindp","unistd.h","","FAR int *"
 "getoptoptp","unistd.h","","FAR int *"
 "gets","stdio.h","defined(CONFIG_FILE_STREAM)","FAR char *","FAR char *"

libs/libc/unistd/Make.defs

@@ -36,9 +36,9 @@
 # Add the unistd C files to the build
 
 CSRCS += lib_access.c lib_daemon.c lib_swab.c lib_pathconf.c lib_sysconf.c
-CSRCS += lib_getopt.c lib_getoptargp.c lib_getoptindp.c lib_getoptoptp.c
-CSRCS += lib_alarm.c lib_fstatvfs.c lib_statvfs.c lib_sleep.c lib_usleep.c
-CSRCS += lib_seteuid.c lib_setegid.c lib_geteuid.c lib_getegid.c
+CSRCS += lib_getopt.c lib_getoptargp.c lib_getopterrp.c lib_getoptindp.c
+CSRCS += lib_getoptoptp.c lib_alarm.c lib_fstatvfs.c lib_statvfs.c lib_sleep.c
+CSRCS += lib_usleep.c lib_seteuid.c lib_setegid.c lib_geteuid.c lib_getegid.c
 CSRCS += lib_setreuid.c lib_setregid.c
 CSRCS += lib_getrusage.c lib_utimes.c
 CSRCS += lib_setrlimit.c lib_getrlimit.c

libs/libc/unistd/lib_getopt.c

@@ -52,6 +52,7 @@
  ****************************************************************************/
 
 FAR char *optarg; /* Optional argument following option */
+int opterr = 0;   /* Print error message */
 int optind = 1;   /* Index into argv */
 int optopt = '?'; /* unrecognized option character */
 

libs/libc/unistd/lib_getopterrp.c

@@ -0,0 +1,45 @@
+/****************************************************************************
+ * libs/libc/unistd/lib_getopterrp.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <unistd.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: getopterrp
+ *
+ * Description:
+ *   Returns a pointer to opterr.  This function is only used for external
+ *   modules that need to access the base, global variable, opterr.
+ *
+ ****************************************************************************/
+
+FAR int *getopterrp(void)
+{
+  return &opterr;
+}