Make relative path relative to the *current* CMake list, not the main one.

src/syncterm/CMakeLists.txt

@@ -40,7 +40,7 @@ set(SOURCE
 
 if(WIN32)
 	list(APPEND SOURCE ../comio/comio_win32.c)
-	include_directories(syncterm PRIVATE ../../3rdp/win32.release/cryptlib/include)
+	list(APPEND CMAKE_REQUIRED_INCLUDES ${CMAKE_CURRENT_LIST_DIR}/../../3rdp/win32.release/cryptlib/include)
 else()
 	list(APPEND SOURCE ../comio/comio_nix.c)
 endif()
@@ -86,9 +86,6 @@ target_include_directories(syncterm PRIVATE ../uifc)
 target_include_directories(syncterm PRIVATE ../sbbs3)
 target_include_directories(syncterm PRIVATE ../comio)
 target_include_directories(syncterm PRIVATE ../smblib)
-if(NOT WIN32)
-#	target_link_libraries(syncterm m)
-endif()
 if(NOT HAS_CRYPTLIB_H)
     target_compile_definitions(syncterm PRIVATE WITHOUT_CRYPTLIB)
 endif()