COMP: wasi doesn't support pthread

Fix 'pthread.h not found' error by disabling
thread support on DCMTK. Set DCMTK_WITH_THREADS = OFF
to disable threads.

Refer to [1] for more details.

[1] WebAssembly/wasi-libc#209

Modules/ThirdParty/DCMTK/CMakeLists.txt

@@ -342,6 +342,7 @@ endforeach()
     -DCMAKE_RUNTIME_OUTPUT_DIRECTORY:PATH=${CMAKE_RUNTIME_OUTPUT_DIRECTORY}
     -DCMAKE_INSTALL_PREFIX:PATH=${CMAKE_INSTALL_PREFIX}
     -DCMAKE_CXX_FLAGS:STRING=${DCMTK_CXX_FLAGS}
+    -DDCMTK_WITH_THREADS:BOOL=${DCMTK_WITH_THREADS}
     ${CHARSET_CONVERSION_ARGS}
     DEPENDS ${JPEG_DEPENDENCY} ${PNG_DEPENDENCY} ${TIFF_DEPENDENCY} ${ICU_DEPENDENCY}
     BUILD_BYPRODUCTS ${DCMTK_BYPRODUCTS}