Improve DSN whitespace parsing

Author: JanJakes

tests/WP_PDO_MySQL_On_SQLite_PDO_API_Tests.php

@@ -30,7 +30,7 @@ public function test_dsn_parsing(): void {
 		$this->assertSame( 'wp', $driver->query( 'SELECT DATABASE()' )->fetch()[0] );
 
 		// DSN with whitespace before argument names.
-		$driver = new WP_PDO_MySQL_On_SQLite( "mysql-on-sqlite:  path=:memory:;\t dbname=wp" );
+		$driver = new WP_PDO_MySQL_On_SQLite( "mysql-on-sqlite:  path=:memory:; \n\r\t\v\fdbname=wp" );
 		$this->assertSame( 'wp', $driver->query( 'SELECT DATABASE()' )->fetch()[0] );
 
 		// DSN with whitespace in the database name.

wp-includes/sqlite-ast/class-wp-pdo-mysql-on-sqlite.php

@@ -623,8 +623,9 @@ public function __construct(
 			// Restore quoted semicolons that were replaced with "\0".
 			$arg = str_replace( "\0", ';', $arg );
 
-			// PDO DSN allows whitespace before argument name.
-			$arg = ltrim( $arg );
+			// PDO DSN allows whitespace before argument name. Trim characters
+			// as per the "isspace()" C function (in the default "C" locale).
+			$arg = ltrim( $arg, " \n\r\t\v\f" );
 
 			if ( '' === $arg ) {
 				continue;