cmake: build performance tests only with release build

Note that targets for running performance tests are generated only when
CMAKE_BUILD_TYPE is equal to Release or RelWithDebug. Additionally, C++
performance tests require Google Benchmark library. Using non-debug
build and having installed Google Benchmark library is rare case, so I
suppose we don't need to introduce CMake option for performance testing.

NO_CHANGELOG=testing
NO_DOC=testing
NO_TEST=testing infrastructure

(cherry picked from commit a63d291b)