An error in building Angora

[MoonLight-SteinsGate]

When I run ./build/build.sh to build Angora and compile runtime v1.2.2, there is an error that "error: could not find native static library context, perhaps an -L flag is missing?". The information is detailed below:

root@moonlight:~/Angora# ./build/build.sh
++ command -v llvm-config

• '[' -x /root/clang+llvm/bin/llvm-config ']'
• PREFIX=/root/Angora/bin/
• cargo build
  Compiling autocfg v0.1.6
  Compiling proc-macro2 v1.0.2
  Compiling memchr v2.2.1
  Compiling unicode-xid v0.2.0
  Compiling libc v0.2.62
  Compiling byteorder v1.3.2
  Compiling syn v1.0.5
  Compiling serde v1.0.99
  Compiling getrandom v0.1.11
  Compiling proc-macro2 v0.4.30
  Compiling log v0.4.8
  Compiling winapi v0.3.8
  Compiling cfg-if v0.1.9
  Compiling cgmath v0.16.1
  Compiling unicode-xid v0.1.0
  Compiling bitflags v1.1.0
  Compiling lazy_static v1.4.0
  Compiling ryu v1.0.0
  Compiling syn v0.15.44
  Compiling regex-syntax v0.6.12
  Compiling ppv-lite86 v0.2.5
  Compiling approx v0.1.1
  Compiling quick-error v1.2.2
  Compiling nix v0.14.1
  Compiling rgb v0.8.14
  Compiling unicode-width v0.1.6
  Compiling void v1.0.2
  Compiling termcolor v1.0.5
  Compiling cc v1.0.42
  Compiling ansi_term v0.11.0
  Compiling itoa v0.4.4
  Compiling vec_map v0.8.1
  Compiling strsim v0.8.0
  Compiling indexmap v0.4.1
  Compiling unchecked-index v0.2.2
  Compiling num-traits v0.2.8
  Compiling num-integer v0.1.41
  Compiling bincode v1.1.4
  Compiling thread_local v0.3.6
  Compiling c2-chacha v0.2.2
  Compiling humantime v1.2.0
  Compiling textwrap v0.11.0
  Compiling priority-queue v0.6.0
  Compiling runtime_fast v1.2.2 (/root/Angora/runtime_fast)
  Compiling aho-corasick v0.7.6
  Compiling twoway v0.2.0
  Compiling rand v0.4.6
  Compiling atty v0.2.13
  Compiling time v0.1.42
  Compiling memmap v0.7.0
  Compiling wait-timeout v0.2.0
  Compiling num_cpus v1.10.1
  Compiling quote v1.0.2
  Compiling quote v0.6.13
  Compiling rand_core v0.5.1
  Compiling clap v2.33.0
  Compiling regex v1.3.1
  Compiling rand_chacha v0.2.1
  Compiling rand v0.7.0
  Compiling num-traits v0.1.43
  Compiling serde_json v1.0.40
  Compiling chrono v0.4.9
  Compiling ctrlc v3.1.3
  Compiling env_logger v0.6.2
  Compiling pretty_env_logger v0.3.1
  Compiling derive_more v0.15.0
  Compiling serde_derive v1.0.99
  Compiling ctor v0.1.10
  Compiling winconsole v0.10.0
  Compiling colored v1.8.0
  Compiling angora_common v1.2.2 (/root/Angora/common)
  Compiling runtime v1.2.2 (/root/Angora/runtime)
  error: could not find native static library context, perhaps an -L flag is missing?

error: aborting due to previous error

error: Could not compile runtime_fast.
warning: build failed, waiting for other jobs to finish...
error: build failed

The environment variables are configured as what the README.md says.