doc: buildsystem fixes

- use correct pathes (make gmake dist-docs from toplevel directory work)
- configure detects perl as tools/configure does

Signed-off-by: Christoph Egger <chegger@xxxxxxxxx>
Reviewed-by: Matthew Wilson <msw@xxxxxxxxx>

diff -r f1ed2ada40b8 -r fe9b7562b2c8 config/Docs.mk.in
--- a/config/Docs.mk.in	Tue Mar 12 14:19:36 2013 +0000
+++ b/config/Docs.mk.in	Fri May 10 13:44:43 2013 +0000
@@ -11,3 +11,4 @@
 POD2HTML            := @POD2HTML@
 POD2TEXT            := @POD2TEXT@
 MARKDOWN            := @MARKDOWN@
+PERL                := @PERL@
diff -r f1ed2ada40b8 -r fe9b7562b2c8 docs/Makefile
--- a/docs/Makefile	Tue Mar 12 14:19:36 2013 +0000
+++ b/docs/Makefile	Fri May 10 13:44:43 2013 +0000
@@ -1,5 +1,3 @@
-#!/usr/bin/make -f
-
 XEN_ROOT=$(CURDIR)/..
 include $(XEN_ROOT)/Config.mk
 -include $(XEN_ROOT)/config/Docs.mk
@@ -75,7 +73,7 @@
 
 .PHONY: distclean
 distclean: clean
-	rm -rf ../config/Docs.mk config.log config.status config.cache \
+	rm -rf $(XEN_ROOT)/config/Docs.mk config.log config.status config.cache \
 		autom4te.cache
 
 .PHONY: install
@@ -88,8 +86,8 @@
 	cp -R man5 $(DESTDIR)$(MANDIR)
 	[ ! -d html ] || cp -R html $(DESTDIR)$(DOCDIR)
 
-html/index.html: $(DOC_HTML) ./gen-html-index INDEX
-	perl -w -- ./gen-html-index -i INDEX html $(DOC_HTML)
+html/index.html: $(DOC_HTML) $(CURDIR)/gen-html-index INDEX
+	$(PERL) -w -- $(CURDIR)/gen-html-index -i INDEX html $(DOC_HTML)
 
 html/%.html: %.markdown
 	$(INSTALL_DIR) $(@D)
@@ -123,13 +121,13 @@
 	@echo "pod2html not installed; skipping $<."
 endif
 
-html/hypercall/index.html: ./xen-headers
+html/hypercall/index.html: $(CURDIR)/xen-headers
 	rm -rf $(@D)
 	$(INSTALL_DIR) $(@D)
-	./xen-headers -O $(@D) \
+	$(PERL) -w $(CURDIR)/xen-headers -O $(@D) \
 		-T 'arch-x86_64 - Xen public headers' \
 		-X arch-x86_32 -X xen-x86_32 -X arch-arm \
-		../xen include/public include/xen/errno.h
+		$(XEN_ROOT)/xen include/public include/xen/errno.h
 
 -include html/hypercall/.deps
 
diff -r f1ed2ada40b8 -r fe9b7562b2c8 docs/configure.ac
--- a/docs/configure.ac	Tue Mar 12 14:19:36 2013 +0000
+++ b/docs/configure.ac	Fri May 10 13:44:43 2013 +0000
@@ -10,6 +10,7 @@
 
 # M4 Macro includes
 m4_include([../m4/docs_tool.m4])
+m4_include([../m4/path_or_fail.m4])
 
 AX_DOCS_TOOL_PROG([FIG2DEV], [fig2dev])
 AX_DOCS_TOOL_PROG([POD2MAN], [pod2man])
@@ -17,4 +18,7 @@
 AX_DOCS_TOOL_PROG([POD2TEXT], [pod2text])
 AX_DOCS_TOOL_PROGS([MARKDOWN], [markdown], [markdown markdown_py])
 
+AC_ARG_VAR([PERL], [Path to Perl parser])
+AX_PATH_PROG_OR_FAIL([PERL], [perl])
+
 AC_OUTPUT()