test: Fail more verbosely in cmake-pthread.sh.

test/dioscc/cmake-pthread.sh

@@ -5,4 +5,8 @@ cmake_minimum_required( VERSION 3.2 )
 find_package( Threads REQUIRED )
 EOF
 
-cmake -DCMAKE_C_COMPILER=dioscc -DCMAKE_CXX_COMPILER=dioscc
+if ! cmake -DCMAKE_C_COMPILER=dioscc -DCMAKE_CXX_COMPILER=dioscc .; then
+    cat CMakeFiles/CMakeOutput.log
+    cat CMakeFiles/CMakeError.log
+    exit 1
+fi