Remove dependency on skygw_utils.h

- STRERROR_BUFLEN moved to cdefs.h and renamed to MXS_STRERROR_BUFLEN.
  Better would be to provide a 'const char* mxs_strerror(int errno)'
  that would have a thread specific buffer for the error message.
- MIN and MAX also moved to defs.h as MXS_MIN and MXS_MAX.
- Now only mlist.h of the headers depend upon skygw_utils.h.

server/modules/filter/cache/rules.c

@@ -246,7 +246,7 @@ CACHE_RULES *cache_rules_load(const char *path, uint32_t debug)
     }
     else
     {
-        char errbuf[STRERROR_BUFLEN];
+        char errbuf[MXS_STRERROR_BUFLEN];
 
         MXS_ERROR("Could not open rules file %s for reading: %s",
                   path, strerror_r(errno, errbuf, sizeof(errbuf)));

server/modules/filter/cache/storage/storage_rocksdb/rocksdbstorage.cc

@@ -118,7 +118,7 @@ bool RocksDBStorage::Initialize()
     else if (errno != EEXIST)
     {
         initialized = false;
-        char errbuf[STRERROR_BUFLEN];
+        char errbuf[MXS_STRERROR_BUFLEN];
 
         MXS_ERROR("Failed to create storage directory %s: %s",
                   u_storageDirectory.c_str(),

server/modules/filter/dbfwfilter/dbfwfilter.c

@@ -1173,7 +1173,7 @@ bool define_regex_rule(void* scanner, char* pattern)
     }
     else
     {
-        PCRE2_UCHAR errbuf[STRERROR_BUFLEN];
+        PCRE2_UCHAR errbuf[MXS_STRERROR_BUFLEN];
         pcre2_get_error_message(err, errbuf, sizeof(errbuf));
         MXS_ERROR("dbfwfilter: Invalid regular expression '%s': %s",
                   start, errbuf);
@@ -1343,7 +1343,7 @@ static bool process_rule_file(const char* filename, FW_INSTANCE* instance)
     }
     else
     {
-        char errbuf[STRERROR_BUFLEN];
+        char errbuf[MXS_STRERROR_BUFLEN];
         MXS_ERROR("Failed to open rule file '%s': %d, %s", filename, errno,
                   strerror_r(errno, errbuf, sizeof(errbuf)));
 
@@ -2240,7 +2240,7 @@ routeQuery(FILTER *instance, void *session, GWBUF *queue)
                 int len;
                 if (modutil_extract_SQL(queue, &sql, &len))
                 {
-                    len = MIN(len, FW_MAX_SQL_LEN);
+                    len = MXS_MIN(len, FW_MAX_SQL_LEN);
                     if (match && my_instance->log_match & FW_LOG_MATCH)
                     {
                         ss_dassert(rname);

server/modules/filter/gatekeeper/gatekeeper.c

@@ -183,7 +183,7 @@ static FILTER* createInstance(const char *name, char **options, FILTER_PARAMETER
                 }
                 else
                 {
-                    char err[STRERROR_BUFLEN];
+                    char err[MXS_STRERROR_BUFLEN];
                     MXS_ERROR(MODNAME"File is not accessible: %d, %s", errno,
                               strerror_r(errno, err, sizeof(err)));
                     ok = false;
@@ -453,7 +453,7 @@ static bool write_stored_data(GK_INSTANCE *inst)
             if (write(fd, &len, sizeof(len)) != sizeof(len) ||
                 write(fd, key, len) != len)
             {
-                char err[STRERROR_BUFLEN];
+                char err[MXS_STRERROR_BUFLEN];
                 MXS_ERROR(MODNAME"Failed to write key '%s' to disk (%d, %s). The datafile at '%s' was "
                           "not updated but it will be updated when the next session closes. ",
                           key, errno, strerror_r(errno, err, sizeof(err)), inst->datadir);
@@ -471,7 +471,7 @@ static bool write_stored_data(GK_INSTANCE *inst)
 
             if (!rval)
             {
-                char err[STRERROR_BUFLEN];
+                char err[MXS_STRERROR_BUFLEN];
                 MXS_ERROR(MODNAME"Failed to rename file '%s' to '%s' when writing data: %d, %s",
                           filepath, newfilepath, errno, strerror_r(errno, err, sizeof(err)));
             }
@@ -479,7 +479,7 @@ static bool write_stored_data(GK_INSTANCE *inst)
     }
     else if (fd == -1)
     {
-        char err[STRERROR_BUFLEN];
+        char err[MXS_STRERROR_BUFLEN];
         MXS_ERROR(MODNAME"Failed to open file '%s' when writing data: %d, %s",
                   filepath, errno, strerror_r(errno, err, sizeof(err)));
     }
@@ -497,7 +497,7 @@ static void report_failed_read(FILE *file, int nexpected, int nread)
 {
     if (ferror(file))
     {
-        char err[STRERROR_BUFLEN];
+        char err[MXS_STRERROR_BUFLEN];
         MXS_ERROR(MODNAME"Failed to read %d bytes, only %d bytes read: %d, %s",
                   nexpected, nread, errno, strerror_r(errno, err, sizeof(err)));
     }
@@ -579,7 +579,7 @@ static bool read_stored_data(GK_INSTANCE *inst)
     }
     else
     {
-        char err[STRERROR_BUFLEN];
+        char err[MXS_STRERROR_BUFLEN];
         MXS_ERROR(MODNAME"Failed to open file '%s' when reading stored data: %d, %s",
                   filepath, errno, strerror_r(errno, err, sizeof(err)));
     }

server/modules/filter/qlafilter/qlafilter.c

@@ -350,7 +350,7 @@ newSession(FILTER *instance, SESSION *session)
 
             if (my_session->fp == NULL)
             {
-                char errbuf[STRERROR_BUFLEN];
+                char errbuf[MXS_STRERROR_BUFLEN];
                 MXS_ERROR("Opening output file for qla "
                           "fileter failed due to %d, %s",
                           errno,
@@ -363,7 +363,7 @@ newSession(FILTER *instance, SESSION *session)
     }
     else
     {
-        char errbuf[STRERROR_BUFLEN];
+        char errbuf[MXS_STRERROR_BUFLEN];
         MXS_ERROR("Memory allocation for qla filter failed due to "
                   "%d, %s.",
                   errno,