Set proper file type attribute for OSX zip export

The missing file type in file attributes was causing the file to lose
executable permissions when unzipped with some softwares.

(cherry picked from commit 4501771fd8743e5019fe313e7e6f890d0d68cbd8)

platform/osx/export/export.cpp

@@ -753,7 +753,10 @@ void EditorExportPlatformOSX::_zip_folder_recursive(zipFile &p_zip, const String
 			zipfi.tmz_date.tm_sec = time.sec;
 			zipfi.tmz_date.tm_year = date.year;
 			zipfi.dosDate = 0;
-			zipfi.external_fa = (is_executable ? 0755 : 0644) << 16L;
+			// 0100000: regular file type
+			// 0000755: permissions rwxr-xr-x
+			// 0000644: permissions rw-r--r--
+			zipfi.external_fa = (is_executable ? 0100755 : 0100644) << 16L;
 			zipfi.internal_fa = 0;
 
 			zipOpenNewFileInZip4(p_zip,