Attempt to unbreak build_apple_frameworks (#9193)

Not sure why the threadpool extension isn't mentioned or built in here;
we should follow up on that.

Author: swolchok

build/build_apple_frameworks.sh

@@ -53,7 +53,6 @@ libmicrokernels-prod.a,\
 
 FRAMEWORK_KERNELS_CUSTOM="kernels_custom:\
 libcustom_ops.a,\
-libextension_parallel.a,\
 :"
 
 FRAMEWORK_KERNELS_OPTIMIZED="kernels_optimized:\