fix version recorded in releases

If downloaded as a tarball release, there will be no info from git
to determine the release, so it ends up v0.0.0. If that's the case,
we'll now use the release specified in the project() command,
which needs to be updated for each new release.

CMakeLists.txt

@@ -13,7 +13,7 @@ foreach(p
   endif()
 endforeach()
 
-project (benchmark CXX)
+project (benchmark VERSION 1.5.2 LANGUAGES CXX)
 
 option(BENCHMARK_ENABLE_TESTING "Enable testing of the benchmark library." ON)
 option(BENCHMARK_ENABLE_EXCEPTIONS "Enable the use of exceptions in the benchmark library." ON)
@@ -81,8 +81,12 @@ list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 include(GetGitVersion)
 get_git_version(GIT_VERSION)
 
+if ("${GIT_VERSION}" STREQUAL "v0.0.0")
+  set(VERSION "${benchmark_VERSION}")
+else()
+  string(REGEX MATCH "[0-9]+\\.[0-9]+\\.[0-9]+" VERSION ${GIT_VERSION})
+endif()
 # Tell the user what versions we are using
-string(REGEX MATCH "[0-9]+\\.[0-9]+\\.[0-9]+" VERSION ${GIT_VERSION})
 message(STATUS "Version: ${VERSION}")
 
 # The version of the libraries