Disable libunwind doc generation

I think we don't need libunwind to generate doc. And libunwind will call
latex2man and pdflatex to generate its doc. And this can not be disabled
through command line. Please see here: https://bugzilla.mozilla.org/show_bug.cgi?id=738302

.travis.yml

@@ -51,7 +51,6 @@ addons:
     - libtool
     - ninja-build
     - python-dev
-    - texlive-extra-utils
     - libcurl4-openssl-dev
     - libxml2-dev 
     - libxslt1-dev

CMakeLists.txt

@@ -187,6 +187,7 @@ set(LIBUNWIND_PATCHES
   ${CMAKE_SOURCE_DIR}/libunwind_patches/0001-pyston-add-lots-of-comments.patch
   ${CMAKE_SOURCE_DIR}/libunwind_patches/0002-pyston-stop-x86_64-setcontext-restoring-uninitialize.patch
   ${CMAKE_SOURCE_DIR}/libunwind_patches/0003-use-a-sorted-array-for-registered-objects-and-do-a-b.patch
+  ${CMAKE_SOURCE_DIR}/libunwind_patches/0004-disable-libunwind-doc-generation.patch
   ${CMAKE_SOURCE_DIR}/libunwind_patches/9999-is-patched-marker.patch
 )
 

docs/INSTALLING.md

@@ -14,18 +14,18 @@ sudo add-apt-repository --yes ppa:ubuntu-toolchain-r/test
 sudo add-apt-repository --yes ppa:kubuntu-ppa/backports
 sudo apt-get -qq update
 
-sudo apt-get install -yq git cmake ninja-build ccache libncurses5-dev liblzma-dev libreadline-dev libgmp3-dev libmpfr-dev autoconf libtool python-dev texlive-extra-utils clang-3.4 libstdc++-4.8-dev libssl-dev libsqlite3-dev pkg-config libbz2-dev
+sudo apt-get install -yq git cmake ninja-build ccache libncurses5-dev liblzma-dev libreadline-dev libgmp3-dev libmpfr-dev autoconf libtool python-dev clang-3.4 libstdc++-4.8-dev libssl-dev libsqlite3-dev pkg-config libbz2-dev
 ```
 
 
 **Ubuntu 14.04/14.10/15.04**
 ```
-sudo apt-get install -yq automake git cmake ninja-build ccache libncurses5-dev liblzma-dev libreadline-dev libgmp3-dev libmpfr-dev autoconf libtool python-dev texlive-extra-utils clang libssl-dev libsqlite3-dev pkg-config libbz2-dev
+sudo apt-get install -yq automake git cmake ninja-build ccache libncurses5-dev liblzma-dev libreadline-dev libgmp3-dev libmpfr-dev autoconf libtool python-dev clang libssl-dev libsqlite3-dev pkg-config libbz2-dev
 ```
 
 **Fedora 21**
 ```
-sudo yum install git make cmake clang gcc gcc-c++ ccache ninja-build xz-devel automake libtool gmp-devel mpfr-devel readline-devel openssl-devel sqlite-devel python-devel zlib-devel bzip2-devel ncurses-devel texlive-latex2man libffi-devel
+sudo yum install git make cmake clang gcc gcc-c++ ccache ninja-build xz-devel automake libtool gmp-devel mpfr-devel readline-devel openssl-devel sqlite-devel python-devel zlib-devel bzip2-devel ncurses-devel libffi-devel
 ```
 
 ### Additional prerequisites for running the integration tests

libunwind_patches/0004-disable-libunwind-doc-generation.patch

+From 6ec1c9e847dda96f0acda8d63681cbd50f5d2e2b Mon Sep 17 00:00:00 2001
+From: Boxiang Sun <daetalusun@gmail.com>
+Date: Wed, 31 Aug 2016 17:00:49 +0800
+Subject: [PATCH] disable libunwind doc generation.
+
+Currently we don't need libunwind to generate documentation. This can
+avoid to force use install texlive.
+---
+ doc/Makefile.am | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/doc/Makefile.am b/doc/Makefile.am
+index 2534066..3a516c3 100644
+--- a/doc/Makefile.am
++++ b/doc/Makefile.am
+@@ -49,8 +49,8 @@ EXTRA_DIST = NOTES libunwind.trans					\
+ 	_U_dyn_cancel.tex						\
+ 	$(man3_MANS)
+ 
+-L2M	= latex2man
+-L2P	= pdflatex
++L2M	= echo
++L2P	= echo
+ L2M_CMD	= $(L2M) -t $(srcdir)/libunwind.trans
+ L2H_CMD	= $(L2M) -H -t $(srcdir)/libunwind.trans
+ 
+-- 
+1.9.1
+