问题：
我是rails的新手，并试图开始使用rails教程。在升级到不同版本的ruby时，我在尝试将我的ruby版本从1.8.7升级到1.9.3-p374时出现以下错误
错误
Error running 'make', please read /usr/local/rvm/log/ruby-1.9.3-p374/make.log
There has been an error while running make. Halting the installation.
Brew List
apple-gcc42
cmake
libksba
libyaml
readline
autoconf
curl
libtool
make
sqlite
automake
git
libxml2
openssl
bash
libgpg-error
libxslt
pkg-config
GCC版
i686-apple-darwin11-gcc-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5666) (dot 3)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
cpp路径
/usr/bin/cpp
我遵循的步骤