Configure: perl Makefile rebuild after configure.

The $NGX_AUTO_CONFIG_H added to perl module Makefile dependencies to
make sure it's always rebuild after a configure.  It is needed as we
expand various variables used for Makefile generation during configure
(in particular, nginx version).

auto/lib/perl/make

diff --git a/auto/lib/perl/make b/auto/lib/perl/make
index 260bd95..d1c1b9e 100644
--- a/auto/lib/perl/make
+++ b/auto/lib/perl/make
@@ -18,6 +18,7 @@
 
 
 $NGX_OBJS/src/http/modules/perl/Makefile: \\
+		$NGX_AUTO_CONFIG_H \\
 		src/core/nginx.h \\
 		src/http/modules/perl/Makefile.PL \\
 		src/http/modules/perl/nginx.pm \\