Make unit tests run for external build.

No reason for these not to run all the time. Fix
them to build agian.

Tested-by: Unit tests passed.

Change-Id: Ica8ad56dd76b404b0f5fd0207458a042344861cf
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/CMakeLists.txt.in b/CMakeLists.txt.in
index daee06c..1213120 100644
--- a/CMakeLists.txt.in
+++ b/CMakeLists.txt.in
@@ -107,3 +107,12 @@
     "${CMAKE_BINARY_DIR}/prefix/include/" && cp -R
     ${CMAKE_BINARY_DIR}/boost-src/boost ${CMAKE_BINARY_DIR}/prefix/include
 )
+
+externalproject_add (
+    gtest GIT_REPOSITORY "https://github.com/google/googletest.git" GIT_TAG
+    dfa853b63d17c787914b663b50c2095a0c5b706e CMAKE_ARGS
+    -DCMAKE_INSTALL_PREFIX=${CMAKE_BINARY_DIR}/googletest-build SOURCE_DIR
+    "${CMAKE_BINARY_DIR}/googletest-src" BINARY_DIR
+    "${CMAKE_BINARY_DIR}/googletest-build" CMAKE_ARGS
+    -DCMAKE_INSTALL_PREFIX=${CMAKE_BINARY_DIR}/prefix
+)