explicitly specify libdir when configuring jubatus_core and jubatus

[kmaehashi]

This PR fixes the issue that install.sh does not work on 64-bit RHEL-based systems.

waf was upgraded in Jubatus / Core 1.0.2 release (https://github.com/jubatus/jubatus/pull/1181). In recent versions of waf, it automatically guesses the suffix of library directory name. On 64-bit systems which has /usr/lib64 directory (e.g., RHEL, CentOS, etc.), the suffix 64 is used.

https://github.com/waf-project/waf/blob/waf-1.9.7/waflib/Utils.py#L812-L824

So Jubatus Core is installed to $PREFIX/lib64, instead of $PRFEIX/lib. As the installer script expects that all libraries to be installed under $PREFIX/lib, this change caused Jubatus build to fail with the following error (failed to find Jubatus Core installation):

Checking for 'jubatus_core'
['/root/local/bin/pkg-config', '--cflags', '--libs', 'jubatus_core']
err: Package jubatus_core was not found in the pkg-config search path.
Perhaps you should add the directory containing `jubatus_core.pc' to the PKG_CONFIG_PATH environment variable
No package 'jubatus_core' found

[rimms]

👍 I tested this patch on CentOS 7 (x86_64).

• w/ this patch:

  .. snip ..
  Have fun!  -- Jubatus Team

• w/o this patch (develop branch)

  .. snip ..
  Failed to find the library. Please confirm that PKG_CONFIG_PATH environment variable is correctly set.
  (complete log in /root/jubatus-installer/download/jubatus-1.0.3/build/config.log)