perl 5.26 dropped '.' from the module search path (@INC), so to allow
5.34 to find build-time code in ., add '.' to the end of the path
in INC.

--- Authen-PAM-0.16/Makefile.PL.orig
+++ Authen-PAM-0.16/Makefile.PL
@@ -1,6 +1,11 @@
 use ExtUtils::MakeMaker;
 use Config;
 
+# allow perl 5.26 and later to find code relative to .
+BEGIN {
+	push @INC, '.';
+}
+
 sub configure {
     $ENV{'CC'} # If a compiler is not specified on the command line then
       or $ENV{'CC'} = $Config{'cc'}; # use the one with which perl was built