add GL to maybeExport (#5609)

AUTHORS

@@ -269,6 +269,7 @@ a license to everyone to use it as detailed in LICENSE.)
 * Vilibald Wanča <vilibald@wvi.cz>
 * Alex Hixon <alex@alexhixon.com>
 * Vladimir Davidovich <thy.ringo@gmail.com>
+* Yuriy Levchenko <irov13@mail.ru>
 * Dmitry Tolmachov <dmitolm@gmail.com>
 * Dylan McKay <me@dylanmckay.io>
 * Christophe Gragnic <cgragnic@netc.fr>

src/postamble.js

@@ -4,6 +4,7 @@
 Module['asm'] = asm;
 
 {{{ maybeExport('FS') }}}
+{{{ maybeExport('GL') }}}
 
 #if MEM_INIT_METHOD == 2
 #if USE_PTHREADS