Make bpf_conformance CMake Configuration Embeddable (#127)

Because of the use of ${CMAKE_BINARY_DIR} in the root CMakeLists.txt
file, any CMake-based project embedding this project had trouble
locating the bpf_conformance binary.

Signed-off-by: Will Hawkins <hawkinsw@obs.cr>

CMakeLists.txt

@@ -10,9 +10,9 @@ if (IS_DIRECTORY "${PROJECT_SOURCE_DIR}/.git")
        DESTINATION "${PROJECT_SOURCE_DIR}/.git/hooks")
 endif ()
 
-set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
-set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
-set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/bin)
 
 if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
   add_compile_options(/ZH:SHA_256 /guard:cf /Qspectre /sdl)