rbenv install / configure: error: C compiler cannot create executables


エラーログ

```
$ rbenv install 1.9.3-p448
Downloading yaml-0.1.4.tar.gz...
-> http://dqw8nmjcqpjn7.cloudfront.net/36c852831d02cf90508c29852361d01b
Installing yaml-0.1.4...
Installed yaml-0.1.4 to /usr/local/var/rbenv/versions/1.9.3-p448

Downloading ruby-1.9.3-p448.tar.gz...
-> http://cache.ruby-lang.org/pub/ruby/1.9/ruby-1.9.3-p448.tar.gz
Installing ruby-1.9.3-p448...

BUILD FAILED

Inspect or clean up the working tree at /var/folders/_n/g5d3dg1s0rx7sc0vq5lxbgyr0000gn/T/ruby-build.20130926203939.28331
Results logged to /var/folders/_n/g5d3dg1s0rx7sc0vq5lxbgyr0000gn/T/ruby-build.20130926203939.28331.log

Last 10 log lines:
/var/folders/_n/g5d3dg1s0rx7sc0vq5lxbgyr0000gn/T/ruby-build.20130926203939.28331/ruby-1.9.3-p448 /var/folders/_n/g5d3dg1s0rx7sc0vq5lxbgyr0000gn/T/ruby-build.20130926203939.28331 ~/tmp/sinatraapp01
configure: WARNING: unrecognized options: --with-readline-dir, --with-openssl-dir
checking build system type... x86_64-apple-darwin12.5.0
checking host system type... x86_64-apple-darwin12.5.0
checking target system type... x86_64-apple-darwin12.5.0
checking for gcc... gcc
checking whether the C compiler works... no
configure: error: in `/var/folders/_n/g5d3dg1s0rx7sc0vq5lxbgyr0000gn/T/ruby-build.20130926203939.28331/ruby-1.9.3-p448':
configure: error: C compiler cannot create executables
See `config.log' for more details

BUILD FAILED

Inspect or clean up the working tree at /var/folders/_n/g5d3dg1s0rx7sc0vq5lxbgyr0000gn/T/ruby-build.20130926203939.28331
Results logged to /var/folders/_n/g5d3dg1s0rx7sc0vq5lxbgyr0000gn/T/ruby-build.20130926203939.28331.log

Last 10 log lines:
configure: WARNING: unrecognized options: --with-readline-dir, --with-openssl-dir
checking build system type... x86_64-apple-darwin12.5.0
checking host system type... x86_64-apple-darwin12.5.0
checking target system type... x86_64-apple-darwin12.5.0
checking for gcc... gcc
checking whether the C compiler works... no
configure: error: in `/var/folders/_n/g5d3dg1s0rx7sc0vq5lxbgyr0000gn/T/ruby-build.20130926203939.28331/ruby-1.9.3-p448':
configure: error: C compiler cannot create executables
See `config.log' for more details
make: *** No targets specified and no makefile found.  Stop.

```

```
$ /usr/local/bin/gcc -v
Using built-in specs.
COLLECT_GCC=/usr/local/bin/gcc
COLLECT_LTO_WRAPPER=/usr/local/Cellar/gcc49/4.9-20130825/gcc/libexec/gcc/x86_64-apple-darwin12.4.0/4.9.0/lto-wrapper
Target: x86_64-apple-darwin12.4.0
Configured with: ../configure --build=x86_64-apple-darwin12.4.0 --prefix=/usr/local/Cellar/gcc49/4.9-20130825/gcc --datarootdir=/usr/local/Cellar/gcc49/4.9-20130825/share --bindir=/usr/local/Cellar/gcc49/4.9-20130825/bin --enable-languages=c --program-suffix=-4.9 --with-gmp=/usr/local/opt/gmp4 --with-mpfr=/usr/local/opt/mpfr2 --with-mpc=/usr/local/opt/libmpc08 --with-cloog=/usr/local/opt/cloog018 --with-isl=/usr/local/opt/isl011 --with-system-zlib --enable-libstdcxx-time=yes --enable-stage1-checking --enable-checking=release --enable-plugin --enable-lto --disable-werror --disable-nls --disable-multilib
Thread model: posix
gcc version 4.9.0 20130825 (experimental) (GCC) 
```

GCCのバージョンが原因っぽいので指定する

```
$ CC=/usr/bin/gcc rbenv install 1.9.3-p448
```