build: support static libclosure builds

While we are still undecided on the state of libclosure (whether it
should be supported as a dynamic-only linked dependency or whether we
should support statically linking against the library), tweak the build
to support the static builds on Windows.

Author: compnerd

src/BlocksRuntime/CMakeLists.txt

@@ -7,8 +7,11 @@ if(WIN32)
     BlocksRuntime.def)
 
   if(NOT BUILD_SHARED_LIBS)
-    target_compile_definitions(BlocksRuntime PRIVATE
+    target_compile_definitions(BlocksRuntime PUBLIC
       BlocksRuntime_STATIC)
+    target_compile_options(BlocksRuntime PUBLIC
+      "$<$<COMPILE_LANGUAGE:C,CXX>:SHELL:$<$<BOOL:${MSVC}>:-Xclang >-static-libclosure>"
+      $<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xcc -static-libclosure>)
   endif()
 endif()