While `#:in-original-place? #t` provides one way to serialize
foreign calls, it acts as a single lock and requires expensive
context switches. Using an explicit lock can be more efficient
for serializing calls across different places.
For example, running "plot.scrbl" takes 70 seconds on my machine
in the original place and using `#:lock-name` in any place,
while it took 162 seconds in a non-main place with Cairo+Pango
serialization via `#:in-original-place? #t`.
Internally, the named lock combines compare-and-swap with a
place channel. That strategy gives good performance in the case
of no contention, and it cooperates properly with the Racket
scheduler where there is contention.
