Bump third_party/pigweed/repo from `0380161` to `a2c5384` #392

Job	Run time
REPL Tests - Darwin	0s
REPL Tests - Linux	38m 56s
Test Suites - Darwin (no-ble-asan-clang)	1h 21m 5s
Test Suites - Linux (no-ble-tsan-clang)	1h 33m 1s
Test Suites - Darwin (no-ble-tsan-clang)	2h 14m 13s
	5h 47m 15s

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