net/rubygem-grpc: fix build with clang 16
Clang 16 has a new error about incompatible function types, which shows
up when building net/rubygem-grpc:
rb_channel.c:764:40: error: incompatible function pointer types passing 'VALUE (VALUE)' (aka 'unsigned long (unsigned long)') to parameter of type 'VALUE (*)(void *)' (aka 'unsigned long (*)(void *)') [-Wincompatible-function-pointer-types]
background_thread = rb_thread_create(run_poll_channels_loop, NULL);
^~~~~~~~~~~~~~~~~~~~~~
/usr/local/include/ruby-3.1/ruby/internal/intern/thread.h:190:32: note: passing argument to parameter 'f' here
VALUE rb_thread_create(VALUE (*f)(void *g), void *g);
^Fix it by adjusting the parameters for the thread callback functions.
PR: 271540
Approved by: sunpoet (maintainer)
MFH: 2023Q2