test_emdawnwebgpu_link_test is flaky

[sbc100]

This error showed up on the emscripten-releases bots recently:

system_libs:INFO: compiled 1 inputs in 0.54s
cache:INFO:  - ok
cache:INFO: deleting cached file: /Volumes/Work/s/w/ir/x/w/install/emscripten/cache/sysroot/lib/wasm32-emscripten/libemdawnwebgpu-00c5e8e9-O0.a
ports:INFO: retrieving port: mpg123 from https://www.mpg123.de/download/mpg123-1.26.2.tar.bz2
test_embind_tsgen_val (test_other.other) ... ok (7.87s)
wasm-ld: error: cannot open /Volumes/Work/s/w/ir/x/w/install/emscripten/cache/sysroot/lib/wasm32-emscripten/libemdawnwebgpu-00c5e8e9-O0.a: No such file or directory
em++: error: '/Volumes/Work/s/w/ir/x/w/install/bin/wasm-ld -o a.out.wasm /Volumes/Work/s/w/ir/x/t/emtest_tmwyofnz/emscripten_temp_ushsxhk4/test_emdawnwebgpu_link_test_0.o -L/Volumes/Work/s/w/ir/x/w/install/emscripten/cache/sysroot/lib/wasm32-emscripten -L/Volumes/Work/s/w/ir/x/w/install/emscripten/src/lib /Volumes/Work/s/w/ir/x/w/install/emscripten/cache/sysroot/lib/wasm32-emscripten/libemdawnwebgpu-00c5e8e9-O0.a -lGL-getprocaddr -lal -lhtml5 -lstubs-debug -lnoexit -lc-debug -ldlmalloc-debug -lcompiler_rt -lc++-debug-noexcept -lc++abi-debug-noexcept -lsockets -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr /Volumes/Work/s/w/ir/x/t/emtest_tmwyofnz/tmpwk4_fj7klibemscripten_js_symbols.so --export=emscripten_stack_get_end --export=emscripten_stack_get_free --export=emscripten_stack_get_base --export=emscripten_stack_get_current --export=emscripten_stack_init --export=_emscripten_stack_alloc --export=__wasm_call_ctors --export=_emscripten_stack_restore --export=malloc --export=free --export-if-defined=__start_em_asm --export-if-defined=__stop_em_asm --export-if-defined=__start_em_lib_deps --export-if-defined=__stop_em_lib_deps --export-if-defined=__start_em_js --export-if-defined=__stop_em_js --export-if-defined=main --export-if-defined=__main_argc_argv --export-if-defined=fflush --export-table -z stack-size=65536 --no-growable-memory --initial-heap=16777216 --no-entry --stack-first --table-base=1' failed (returned 1)
None
None
test_emdawnwebgpu_link_test_closure_assertions (test_other.other) ... FAIL

It looks like maybe one is deleting a file that another test is going to use. See deleting cached file: /Volumes/Work/s/w/ir/x/w/install/emscripten/cache/sysroot/lib/wasm32-emscripten/libemdawnwebgpu-00c5e8e9-O0.a

[juj]

I see this same behavior pop up occassionally on libSDL2 in the parallel tests.. one test is deleting libSDL2.a from cache while another test has just built it there and is attempting to use it.