Add support for defining a Spatial reference system for a Point column.

See: https://mysqlserverteam.com/spatial-reference-systems-in-mysql-8-0/
See: https://dev.mysql.com/doc/refman/8.0/en/spatial-reference-systems.html

src/Illuminate/Database/Schema/Blueprint.php

@@ -1061,12 +1061,13 @@ public function geometry($column)
     /**
      * Create a new point column on the table.
      *
-     * @param  string  $column
+     * @param  string $column
+     * @param  null|int $srid
      * @return \Illuminate\Support\Fluent
      */
-    public function point($column)
+    public function point($column, $srid = null)
     {
-        return $this->addColumn('point', $column);
+        return $this->addColumn('point', $column, compact('srid'));
     }
 
     /**

src/Illuminate/Database/Schema/Grammars/MySqlGrammar.php

@@ -15,7 +15,7 @@ class MySqlGrammar extends Grammar
      */
     protected $modifiers = [
         'Unsigned', 'VirtualAs', 'StoredAs', 'Charset', 'Collate', 'Nullable',
-        'Default', 'Increment', 'Comment', 'After', 'First',
+        'Default', 'Increment', 'Comment', 'After', 'First', 'Srid',
     ];
 
     /**
@@ -966,6 +966,20 @@ protected function modifyComment(Blueprint $blueprint, Fluent $column)
         }
     }
 
+    /**
+     * Get the SQL for a SRID column modifier.
+     *
+     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
+     * @param  \Illuminate\Support\Fluent  $column
+     * @return string|null
+     */
+    protected function modifySrid(Blueprint $blueprint, Fluent $column)
+    {
+        if (! is_null($column->srid) && is_int($column->srid) && $column->srid > 0) {
+            return ' srid '. $column->srid;
+        }
+    }
+
     /**
      * Wrap a single string in keyword identifiers.
      *