fix compilation error in openai#69

Problem:
As mentioned in [this comment](openai#69 (comment)) of openai#69, a compilation crashes due to an error of unused variables on Apple silicon (with clang 14 and possibly 13+). This issue has been reported [elsewhere](ClickHouse/ClickHouse#27705). This seems to be caused by breaking behavior in clang 13 which escalates unused variable from a warning in prior versions to an error.

The solution implemented here:
I add an additional cflags `-Wno-unused-but-set-variable` for apple platforms. 

Tested on macOS 13.3.1 with Apple clang version 14.0.3 (clang-1403.0.22.14.1)

procgen/CMakeLists.txt

@@ -16,7 +16,7 @@ if(APPLE)
   # clang defaults to 20 errors, but usually only the first one is useful
   add_compile_options(-ferror-limit=1)
   # only produce errors on mac where development is done
-  add_compile_options(-Werror -Wextra -Wshadow -Wall -Wformat=2 -Wundef -Wvla -Wmissing-include-dirs -Wnon-virtual-dtor -Wno-unused-parameter)
+  add_compile_options(-Werror -Wextra -Wshadow -Wall -Wformat=2 -Wundef -Wvla -Wmissing-include-dirs -Wnon-virtual-dtor -Wno-unused-parameter -Wno-unused-but-set-variable)
 endif()
 
 if(MSVC)
@@ -75,4 +75,4 @@ add_library(env
 # find libenv.h header
 target_include_directories(env PUBLIC ${LIBENV_DIR})
 
-target_link_libraries(env Qt5::Gui)
+target_link_libraries(env Qt5::Gui)