Fix to support git worktree.

* autogen.sh, Makefile.am, doc/Makefile.am: Use -e for testing .git.

--
Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

Makefile.am

@@ -120,7 +120,7 @@ endif
 gen_start_date = 2011-12-01T06:00:00
 .PHONY: gen-ChangeLog
 gen-ChangeLog:
-	if test -d $(top_srcdir)/.git; then				\
+	if test -e $(top_srcdir)/.git; then				\
 	  (cd $(top_srcdir) &&                      			\
 	    $(GITLOG_TO_CHANGELOG) --append-dot --tear-off		\
 	    --amend=build-aux/git-log-fix 				\

autogen.sh

@@ -214,7 +214,7 @@ if [ "$myhost" = "find-version" ]; then
     esac
 
     beta=no
-    if [ -d .git ]; then
+    if [ -e .git ]; then
       ingit=yes
       tmp=$(git describe --match "${matchstr1}" --long 2>/dev/null)
       if [ -n "$tmp" ]; then

doc/Makefile.am

@@ -136,7 +136,7 @@ dist-hook: defsincdate
 
 defsincdate: $(gnupg_TEXINFOS)
 	: >defsincdate ; \
-	if test -d $(top_srcdir)/.git; then \
+	if test -e $(top_srcdir)/.git; then \
 	  (cd $(srcdir) && git log -1 --format='%ct' \
                -- $(gnupg_TEXINFOS) 2>/dev/null) >>defsincdate; \
 	fi