Fix debug builds, and default to debug.

CMake does weird things if CMAKE_BUILD_TYPE isn't defined and a
multi-whatzit generator is used.

3rdp/build/CMakeLists-cl.txt

@@ -507,3 +507,4 @@ target_compile_definitions(cl INTERFACE STATIC_LIB)
 target_include_directories(cl PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
 target_include_directories(cl INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
 target_link_libraries(cl ${CMAKE_THREAD_LIBS_INIT})
+target_link_libraries(cl $<$<CONFIG:Debug>:dbghelp>)

src/syncterm/CMakeLists.txt

 cmake_minimum_required(VERSION 3.5)
+set(CMAKE_BUILD_TYPE "Debug" CACHE STRING "Choose the build type")
 project (SyncTERM C)
 
 set(WITHOUT_CRYPTLIB OFF CACHE BOOL "Disable cryptlib (ssh and telnet over TLS")