Update to compiletest_rs 0.2.6
Update to compiletest_rs 0.2.6

aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust