Set PKG_CONFIG_PATH instead of copying

Author: CodaFi

.travis.yml

@@ -16,7 +16,7 @@ matrix:
       sudo: required
       dist: trusty
       before_install:
-        - cp ./cllvm.pc /usr/local/lib/pkgconfig/cllvm.pc
+        - export PKG_CONFIG_PATH=${PWD}:"${PKG_CONFIG_PATH}"
         - sudo aptitude install llvm
         - wget -q -O - https://swift.org/keys/all-keys.asc | gpg --import -
         - wget https://swift.org/builds/swift-3.0-release/ubuntu1404/swift-3.0-RELEASE/swift-3.0-RELEASE-ubuntu14.04.tar.gz