Bump third_party/pigweed/repo from `d5fcc90` to `c221c63` #395

Job	Run time
Build framework (macos-release, -sdk macosx -configuration Release)	30m 8s
Build framework (ios-release, -sdk iphoneos -configuration Release)	14m 49s
Build framework (tvos-debug, -sdk appletvos -configuration Debug)	13m 16s
Build framework (watchos-debug, -sdk watchos -configuration Debug)	15m 54s
Run framework tests (asan, -enableAddressSanitizer YES -enableUndefinedBehaviorSanitizer YES)	31m 28s
Run framework tests (tsan, -enableThreadSanitizer YES)	48m 1s
Run framework tests (leaks, ENABLE_LEAK_DETECTION=1)	42m 26s
	3h 16m 2s

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