Add podspec for C-Library.

Summary: This is the first step to adding cocoapods support to YogaKit. We are going to publish a `Yoga` framework to the store that we can use as a dependency. This will also allow developers to build their own abstractions easily using the core API.

Reviewed By: nlutsenko, emilsjolander

Differential Revision: D4466788

fbshipit-source-id: 8f08bdbf524e57c88f7fc3400c4ba6ad58f98d7f

.swift-version

@@ -0,0 +1 @@
+3.0

Yoga.podspec

@@ -0,0 +1,27 @@
+Pod::Spec.new do |s|
+  s.name = 'Yoga'
+  s.version = '1.0.0'
+  s.summary = 'A cross-platform layout engine.'
+  s.homepage = 'https://github.com/facebook/yoga'
+  s.documentation_url = 'https://facebook.github.io/yoga'
+  s.description = 'Yoga is a cross-platform layout engine enabling maximum collaboration within your team by implementing an API many designers are familiar with, and opening it up to developers across different platforms.'
+
+  s.license =  { :type => 'BSD', :file => "LICENSE" }
+  s.authors = 'Facebook'
+  s.social_media_url = 'https://twitter.com/fbOpenSource'
+  s.source = {
+    :git => 'https://github.com/facebook/yoga.git',
+    :tag => 'v2017.01.23.00',
+  }
+  s.module_name = 'yoga'
+  s.requires_arc = false
+  s.compiler_flags = [
+      '-fno-omit-frame-pointer',
+      '-fexceptions',
+      '-Wall',
+      '-Werror',
+      '-std=c11',
+      '-fPIC'
+  ]
+  s.source_files = 'yoga/**/*.{c,h}'
+end