Support RocketChip build Chisel from source #773

Job	Run time
jtag-dtm-test (freechips.rocketchip.system.WithJtagDTMSystem_freechips.rocketchip.system.DefaultC...	10m 19s
jtag-dtm-test (freechips.rocketchip.system.WithJtagDTMSystem_freechips.rocketchip.system.DefaultR...	10m 36s
riscv-arch-test	0s
jtag-dtm-test (freechips.rocketchip.system.WithJtagDTMSystem_freechips.rocketchip.system.WithDebu...	10m 36s
emulator (DefaultSmallConfig)	10m 57s
jtag-dtm-test (freechips.rocketchip.system.WithJtagDTMSystem_freechips.rocketchip.system.WithDebu...	10m 38s
riscv-tests (DefaultConfig)	10m 38s
emulator (DualBankConfig)	11m 2s
riscv-tests (DefaultBufferlessConfig)	10m 29s
emulator (DualChannelConfig)	10m 45s
riscv-tests (DefaultRV32Config)	10m 31s
emulator (DualChannelDualBankConfig)	10m 59s
emulator (RoccExampleConfig)	10m 57s
riscv-tests (TinyConfig)	10m 45s
riscv-tests (DefaultFP16Config)	10m 43s
emulator (Edge128BitConfig)	11m 1s
emulator (Edge32BitConfig)	10m 51s
emulator (QuadChannelBenchmarkConfig)	10m 58s
emulator (EightChannelConfig)	10m 52s
emulator (DualCoreConfig)	10m 59s
emulator (MemPortOnlyConfig)	10m 42s
emulator (MMIOPortOnlyConfig)	10m 50s
emulator (CloneTileConfig)	10m 59s
emulator (HypervisorConfig)	10m 58s
	4h 8m 5s

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