Handle the case when there is no processor info in `/proc/cpuinfo`

`grep -c` would correctly output "0", which is handled specially later
on, but would also exit with a nonzero status which would abort the
script. Piping the output to `wc` to do the counting makes the exit
status of grep irrelevant.

Fixes #447
Add a definition for JRuby 1.7.7
Merge pull request #449 from deepj/master

Add a definition for JRuby 1.7.7
Create jruby-1.7.8
Merge pull request #450 from ketan/jruby-1.7.8

Add definition for jruby-1.7.8
ruby-build 20131115
Add rbx 2.2.0 and 2.2.1 definitions.
Merge pull request #452 from johnbellone/master

Add rbx 2.2.0 and 2.2.1 definitions.
added definition for 1.9.3-p484 and 2.0.0-p353
fix old links
Adds ruby 1.9.3-p484 definition
Adds definition for ruby-2.0.0-p353
Merge pull request #455 from knightq/master

Adds ruby 1.9.3-p484 and ruby 2.0.0-p353 definitions
Fix installing Rubinius 2.0 with Ruby 1.8

Fixes #429, references rubinius/rubinius#2693
Merge branch 'rbx-ruby-18'
Added definition of 2.1.0-preview2
ruby-build 20131122
Update 2.1.0-preview2

Typo fixed
Merge pull request #458 from samgranieri/master

Update 2.1.0-preview2
Ensure $LDFLAGS directories exist for 2.1.0-preview2

Ref. #458

Cf. https://github.com/sstephenson/ruby-build/commit/50bf60f9c2510fbee7f111046e97fe8bf9e66472