http-push: add regression tests

http-push tests require a web server with WebDAV support.

This commit introduces a HTTPD test library, which can be configured using
the following environment variables.

GIT_TEST_HTTPD		enable HTTPD tests
LIB_HTTPD_PATH		web server path
LIB_HTTPD_MODULE_PATH	web server modules path
LIB_HTTPD_PORT		listening port
LIB_HTTPD_DAV		enable DAV
LIB_HTTPD_SVN		enable SVN
LIB_HTTPD_SSL		enable SSL

Signed-off-by: Clemens Buchacher <drizzd@aon.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/lib-httpd/apache.conf

@@ -0,0 +1,34 @@
+PidFile httpd.pid
+DocumentRoot www
+ErrorLog error.log
+
+<IfDefine SSL>
+LoadModule ssl_module modules/mod_ssl.so
+
+SSLCertificateFile httpd.pem
+SSLCertificateKeyFile httpd.pem
+SSLRandomSeed startup file:/dev/urandom 512
+SSLRandomSeed connect file:/dev/urandom 512
+SSLSessionCache none
+SSLMutex file:ssl_mutex
+SSLEngine On
+</IfDefine>
+
+<IfDefine DAV>
+	LoadModule dav_module modules/mod_dav.so
+	LoadModule dav_fs_module modules/mod_dav_fs.so
+
+	DAVLockDB DAVLock
+	<Location />
+		Dav on
+	</Location>
+</IfDefine>
+
+<IfDefine SVN>
+	LoadModule dav_svn_module modules/mod_dav_svn.so
+
+	<Location /svn>
+		DAV svn
+		SVNPath svnrepo
+	</Location>
+</IfDefine>

t/lib-httpd/ssl.cnf

@@ -0,0 +1,8 @@
+RANDFILE                = $ENV::RANDFILE_PATH
+
+[ req ]
+default_bits            = 1024
+distinguished_name      = req_distinguished_name
+prompt                  = no
+[ req_distinguished_name ]
+commonName              = 127.0.0.1