Issue #4279: Fix build of parsermodule under Cygwin.
diff --git a/Parser/printgrammar.c b/Parser/printgrammar.c
index ec8f4da..ae180e1 100644
--- a/Parser/printgrammar.c
+++ b/Parser/printgrammar.c
@@ -16,6 +16,7 @@
 	fprintf(fp, "/* Generated by Parser/pgen */\n\n");
 	fprintf(fp, "#include \"pgenheaders.h\"\n");
 	fprintf(fp, "#include \"grammar.h\"\n");
+	fprintf(fp, "PyAPI_DATA(grammar) _PyParser_Grammar;\n");
 	printdfas(g, fp);
 	printlabels(g, fp);
 	fprintf(fp, "grammar _PyParser_Grammar = {\n");