[PATCH] build: Fix out-of-tree building of documentation.

[Taylan Ulrich Bayırlı/Kammer]

While working on my other patch I noticed we already have some issues
with out-of-tree builds.  Resolved by this patch.

>From 41650754511487f5f1f937317eebd80c19ca8bf1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Taylan=20Ulrich=20Bay=C4=B1rl=C4=B1/Kammer?=
 <address@hidden>
Date: Sat, 9 Jan 2016 15:56:23 +0100
Subject: [PATCH] build: Fix out-of-tree building of documentation.

* doc.am (.dot.png, .dot.pdf, .dot.eps, .png.eps): Create the directory
  for each target in case of out-of-tree building.
---
 doc.am | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/doc.am b/doc.am
index e3a91cc..04a74a9 100644
--- a/doc.am
+++ b/doc.am
@@ -65,18 +65,22 @@ DOT_OPTIONS =                                       \
   -Nfontsize=9 -Nheight=.1 -Nwidth=.1
 
 .dot.png:
+       $(MKDIR_P) `dirname "$@"`
        $(DOT) -Tpng $(DOT_OPTIONS) < "$<" > "address@hidden"
        mv "address@hidden" "$@"
 
 .dot.pdf:
+       $(MKDIR_P) `dirname "$@"`
        $(DOT) -Tpdf $(DOT_OPTIONS) < "$<" > "address@hidden"
        mv "address@hidden" "$@"
 
 .dot.eps:
+       $(MKDIR_P) `dirname "$@"`
        $(DOT) -Teps $(DOT_OPTIONS) < "$<" > "address@hidden"
        mv "address@hidden" "$@"
 
 .png.eps:
+       $(MKDIR_P) `dirname "$@"`
        convert "$<" "address@hidden"
        mv "address@hidden" "$@"
 
-- 
2.6.3