Revert use of LINK_LIBRARY:WHOLE_ARCHIVE (#8000)

This was recently added in #7994 but it turns out this is feature only
available in 3.24 or above. Instead, we can fall back to explicit
reference to one of the symbols we want to export.

Author: sbc100

CMakeLists.txt

@@ -536,7 +536,7 @@ if(EMSCRIPTEN)
   # For the emscripten build we link against libbinaryen wih `--whole-archive`.
   # Without this, the EMSCRIPTEN_KEEPALIVE symbols within the library would
   # be ignored.
-  target_link_libraries(binaryen_wasm PRIVATE "$<LINK_LIBRARY:WHOLE_ARCHIVE,binaryen>")
+  target_link_libraries(binaryen_wasm PRIVATE binaryen)
   target_link_libraries(binaryen_wasm PRIVATE "-sFILESYSTEM")
   target_link_libraries(binaryen_wasm PRIVATE "-sEXPORT_NAME=Binaryen")
   target_link_libraries(binaryen_wasm PRIVATE "-sNODERAWFS=0")
@@ -549,7 +549,13 @@ if(EMSCRIPTEN)
   endif()
   target_link_libraries(binaryen_wasm PRIVATE "-sEXPORT_ES6")
   target_link_libraries(binaryen_wasm PRIVATE "-sEXPORTED_RUNTIME_METHODS=stringToUTF8OnStack,stringToAscii")
-  target_link_libraries(binaryen_wasm PRIVATE "-sEXPORTED_FUNCTIONS=_malloc,_free")
+  # Explictly export _i32_load to ensure the binaryen-c.cpp is linked in.
+  # This is the file that contains all the EMSCRIPTEN_KEEPALIVE symbols which
+  # we want to exports, but enless we explictly reference a symbol from it
+  # the linker will ignore the whole library.
+  # TODO(sbc): Replace with `LINK_LIBRARY:WHOLE_ARCHIVE` once we bump the min
+  # cmake version 3.24.
+  target_link_libraries(binaryen_wasm PRIVATE "-sEXPORTED_FUNCTIONS=_malloc,_free,__i32_load")
   target_link_libraries(binaryen_wasm PRIVATE "--post-js=${CMAKE_CURRENT_SOURCE_DIR}/src/js/binaryen.js-post.js")
   target_link_libraries(binaryen_wasm PRIVATE "-msign-ext")
   target_link_libraries(binaryen_wasm PRIVATE "-mbulk-memory")
@@ -567,7 +573,7 @@ if(EMSCRIPTEN)
 
   # binaryen.js JavaScript variant
   add_executable(binaryen_js ${binaryen_HEADERS})
-  target_link_libraries(binaryen_js PRIVATE "$<LINK_LIBRARY:WHOLE_ARCHIVE,binaryen>")
+  target_link_libraries(binaryen_js PRIVATE binaryen)
   target_link_libraries(binaryen_js PRIVATE "-sWASM=0")
   target_link_libraries(binaryen_js PRIVATE "-sWASM_ASYNC_COMPILATION=0")
 
@@ -597,7 +603,7 @@ if(EMSCRIPTEN)
     target_link_libraries(binaryen_js PRIVATE "-sEXPORT_ES6=1")
   endif()
   target_link_libraries(binaryen_js PRIVATE "-sEXPORTED_RUNTIME_METHODS=stringToUTF8OnStack,stringToAscii")
-  target_link_libraries(binaryen_js PRIVATE "-sEXPORTED_FUNCTIONS=_malloc,_free")
+  target_link_libraries(binaryen_js PRIVATE "-sEXPORTED_FUNCTIONS=_malloc,_free,__i32_load")
   target_link_libraries(binaryen_js PRIVATE "--post-js=${CMAKE_CURRENT_SOURCE_DIR}/src/js/binaryen.js-post.js")
   # js_of_ocaml needs a specified variable with special comment to provide the library to consumers
   if(JS_OF_OCAML)