Issue #19990: Install test/imghdrdata.
diff --git a/Makefile.pre.in b/Makefile.pre.in
index e97b07b..fdca38e 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1019,6 +1019,7 @@
 		test/audiodata \
 		test/capath test/data \
 		test/cjkencodings test/decimaltestdata test/xmltestdata \
+		test/imghdrdata \
 		test/subprocessdata test/sndhdrdata test/support \
 		test/tracedmodules test/encoded_modules \
 		test/namespace_pkgs \