build fails on AArch64, Fedora 33

[LutzWeischerFujitsu]

[jw@cn05 rethinkdb]$ make VERBOSE=1 -j1
mkdir -p build/release/obj/arch/runtime/ ./build/release/dep/arch/runtime/
/usr/lib64/ccache/c++ -isystem ./build/external/re2_2015-11-01/include -isystem ./build/external/v8_3.30.33.16-patched/include -I./src -pthread "-DPRODUCT_NAME="RethinkDB"" "-D__STDC_LIMIT_MACROS" "-D__STDC_FORMAT_MACROS" -Wall -Wextra -DENABLE_TLS "-DRAPIDJSON_HAS_STDSTRING" "-DRAPIDJSON_PARSE_DEFAULT_FLAGS=kParseFullPrecisionFlag" -D_FILE_OFFSET_BITS=64 -Wnon-virtual-dtor -Wno-deprecated-declarations -std=gnu++0x -Wformat=2 -Wswitch-enum -Wno-array-bounds -Wno-maybe-uninitialized -O3 -DNDEBUG -fno-strict-aliasing -g -DHAS_TERMCAP -I./build/proto -DRETHINKDB_VERSION="2.3.2-windows-beta-587-gec80a1" -DRETHINKDB_CODE_VERSION="2.3.2-windows-beta-587-gec80a1" -isystem ./build/external/gtest_1.7.0/include -c -o build/release/obj/arch/runtime/context_switching.o src/arch/runtime/context_switching.cc
-MP -MQ build/release/obj/arch/runtime/context_switching.o -MD -MF ./build/release/dep/arch/runtime/context_switching.d
src/arch/runtime/context_switching.cc:694:2: error: #error "Unsupported architecture."
694 | #error "Unsupported architecture."
| ^~~~~
src/arch/runtime/context_switching.cc: In constructor 'artificial_stack_t::artificial_stack_t(void (*)(), size_t)':
src/arch/runtime/context_switching.cc:272:28: error: 'min_frame' was not declared in this scope
272 | for (size_t i = 0; i < min_frame; i++) {
| ^~~~~~~~~
src/arch/runtime/context_switching.cc: At global scope:
src/arch/runtime/context_switching.cc:696:1: error: expected string-literal before ')' token
696 | );
| ^
make[1]: *** [src/build.mk:344: build/release/obj/arch/runtime/context_switching.o] Error 1
make: *** [Makefile:53: make] Error 2
[jw@cn05 rethinkdb]$

[srh]

This is probably fixed in v2.4.x branch. I have added a list item to try out the build on Fedora to #6975 (and I will leave this open until I do).