build: add missing comma in node.gyp

This commit adds a missing comma for consistency with the
surrounding lines.

PR-URL: #31959
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>

Author: cjihrig

node.gyp

@@ -620,7 +620,7 @@
         'src/histogram-inl.h',
         'src/js_stream.h',
         'src/large_pages/node_large_page.cc',
-        'src/large_pages/node_large_page.h'
+        'src/large_pages/node_large_page.h',
         'src/memory_tracker.h',
         'src/memory_tracker-inl.h',
         'src/module_wrap.h',