fix(gatsby-starter-blog): Fix global access to graphql in blog starter's 404 (#10923)
fix(gatsby-starter-blog): Fix global access to graphql in blog starter's 404 (#10923)

Global access to `graphql` (which is deprecated) got added accidentally in https://github.com/gatsbyjs/gatsby/pull/10865/files

This fixes that and gets rids of the annoying warning in the output
![screenshot 2019-01-08 22 52 33](https://user-images.githubusercontent.com/7701981/50847634-1af91900-1398-11e9-97f5-a5ea812fc873.png)


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