link pnnx with pthread, fix minmax issue on windows build

tools/pnnx/src/CMakeLists.txt

@@ -463,7 +463,7 @@ endif()
 if(WIN32)
     target_link_libraries(pnnx PRIVATE ${TORCH_LIBRARIES})
 else()
-    target_link_libraries(pnnx PRIVATE ${TORCH_LIBRARIES} dl)
+    target_link_libraries(pnnx PRIVATE ${TORCH_LIBRARIES} pthread dl)
 endif()
 
 #set_target_properties(pnnx PROPERTIES COMPILE_FLAGS -fsanitize=address)

tools/pnnx/src/main.cpp

@@ -16,6 +16,7 @@
 
 #if _WIN32
 #include <windows.h>
+#include <c10/util/win32-headers.h>
 #else
 #include <dlfcn.h>
 #endif