Add conformance tests for cl_khr_extended_versioning (#548)

Tests that the new queries work, and that what they return is consistent with
the information returned by the string-based queries.

Signed-off-by: Einar Hov <einar.hov@arm.com>

test_conformance/computeinfo/CMakeLists.txt

@@ -2,6 +2,7 @@ set(MODULE_NAME computeinfo)
 
 set(${MODULE_NAME}_SOURCES
         main.c
+        extended_versioning.cpp
 )
 
 include(../CMakeCommon.txt)