t/lib-httpd: handle running under --valgrind

Running the http tests with valgrind does not work for two
reasons:

  1. Apache complains about following the symbolic link from
     git-http-backend to valgrind.sh.

  2. Apache does not pass through the GIT_VALGRIND variable
     to the backend CGI.

This patch fixes both problems. Unfortunately, there is a
slight hack we need to handle passing environment variables
through Apache. If we just tell it:

  PassEnv GIT_VALGRIND

then Apache will complain when GIT_VALGRIND is not set. If
we try:

  SetEnv GIT_VALGRIND ${GIT_VALGRIND}

then when GIT_VALGRIND is not set, it will pass through the
literal "${GIT_VALGRIND}". Instead, we now unconditionally
pass through GIT_VALGRIND from lib-httpd.sh into apache,
even if it is empty.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

t/lib-httpd.sh

@@ -43,6 +43,10 @@ TEST_PATH="$TEST_DIRECTORY"/lib-httpd
 HTTPD_ROOT_PATH="$PWD"/httpd
 HTTPD_DOCUMENT_ROOT_PATH=$HTTPD_ROOT_PATH/www
 
+# hack to suppress apache PassEnv warnings
+GIT_VALGRIND=$GIT_VALGRIND; export GIT_VALGRIND
+GIT_VALGRIND_OPTIONS=$GIT_VALGRIND_OPTIONS; export GIT_VALGRIND_OPTIONS
+
 if ! test -x "$LIB_HTTPD_PATH"
 then
 	skip_all="skipping test, no web server found at '$LIB_HTTPD_PATH'"

t/lib-httpd/apache.conf

@@ -42,6 +42,9 @@ ErrorLog error.log
 </IfModule>
 </IfVersion>
 
+PassEnv GIT_VALGRIND
+PassEnv GIT_VALGRIND_OPTIONS
+
 Alias /dumb/ www/
 Alias /auth/ www/auth/
 
@@ -62,7 +65,7 @@ ScriptAlias /smart/ ${GIT_EXEC_PATH}/git-http-backend/
 ScriptAlias /smart_noexport/ ${GIT_EXEC_PATH}/git-http-backend/
 ScriptAlias /smart_custom_env/ ${GIT_EXEC_PATH}/git-http-backend/
 <Directory ${GIT_EXEC_PATH}>
-	Options None
+	Options FollowSymlinks
 </Directory>
 <Files ${GIT_EXEC_PATH}/git-http-backend>
 	Options ExecCGI