ction with -source 1.6
    [javac] /builddir/build/BUILD/lz4-java-1.3.0/src/java-unsafe/net/jpountz/util/UnsafeUtils.java:22: warning: Unsafe is internal proprietary API and may be removed in a future release
    [javac] import sun.misc.Unsafe;
    [javac]                ^
    [javac] /builddir/build/BUILD/lz4-java-1.3.0/src/java-unsafe/net/jpountz/util/UnsafeUtils.java:27: warning: Unsafe is internal proprietary API and may be removed in a future release
    [javac]   private static final Unsafe UNSAFE;
    [javac]                        ^
    [javac] /builddir/build/BUILD/lz4-java-1.3.0/src/java-unsafe/net/jpountz/util/UnsafeUtils.java:37: warning: Unsafe is internal proprietary API and may be removed in a future release
    [javac]       Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
    [javac]                         ^
    [javac] /builddir/build/BUILD/lz4-java-1.3.0/src/java-unsafe/net/jpountz/util/UnsafeUtils.java:39: warning: Unsafe is internal proprietary API and may be removed in a future release
    [javac]       UNSAFE = (Unsafe) theUnsafe.get(null);
    [javac]                 ^
    [javac] 5 warnings
    [mkdir] Created dir: /builddir/build/BUILD/lz4-java-1.3.0/build/generated-classes
    [javac] Compiling 16 source files to /builddir/build/BUILD/lz4-java-1.3.0/build/generated-classes
    [javac] warning: [options] bootstrap class path not set in conjunction with -source 1.6
    [javac] 1 warning
install-cpptasks:
[ivy:cachepath] :: resolving dependencies :: ant-contrib#cpptasks-caller;working
[ivy:cachepath] 	confs: [default]
[ivy:cachepath] 	found ant-contrib#cpptasks;SYSTEM in xmvn
[ivy:cachepath] 	[SYSTEM] ant-contrib#cpptasks;1.0b5 (forced)
[ivy:cachepath] 	found org.apache.ant#ant;SYSTEM in xmvn
[ivy:cachepath] 	[SYSTEM] org.apache.ant#ant;1.6.5 (forced)
[ivy:cachepath] 	found org.apache.ant#ant-launcher;SYSTEM in xmvn
[ivy:cachepath] 	[SYSTEM] org.apache.ant#ant-launcher;1.10.5 (forced)
[ivy:cachepath] 	found xerces#xercesImpl;SYSTEM in xmvn
[ivy:cachepath] 	[SYSTEM] xerces#xercesImpl;2.8.1 (forced)
[ivy:cachepath] 	found xml-apis#xml-apis;SYSTEM in xmvn
[ivy:cachepath] 	[SYSTEM] xml-apis#xml-apis;1.4.01 (forced)
[ivy:cachepath] :: resolution report :: resolve 2970ms :: artifacts dl 63ms
	---------------------------------------------------------------------
	|                  |            modules            ||   artifacts   |
	|       conf       | number| search|dwnlded|evicted|| number|dwnlded|
	---------------------------------------------------------------------
	|      default     |   5   |   5   |   0   |   0   ||   5   |   5   |
	---------------------------------------------------------------------
generate-headers:
    [mkdir] Created dir: /builddir/build/BUILD/lz4-java-1.3.0/build/jni-headers
compile-jni:
    [mkdir] Created dir: /builddir/build/BUILD/lz4-java-1.3.0/build/objects
    [mkdir] Created dir: /builddir/build/BUILD/lz4-java-1.3.0/build/jni/linux/riscv64
[cpptasks:cc] 5 total files to be compiled.
BUILDSTDERR: BUILD FAILED
BUILDSTDERR: /builddir/build/BUILD/lz4-java-1.3.0/build.xml:172: Could not launch gcc: java.io.IOException: Cannot run program "gcc" (in directory "/builddir/build/BUILD/lz4-java-1.3.0/build/objects"): error=2, No such file or directory
BUILDSTDERR: Total time: 2 minutes 40 seconds
RPM build errors:
BUILDSTDERR: error: Bad exit status from /var/tmp/rpm-tmp.xfk6P4 (%build)
BUILDSTDERR:     Bad exit status from /var/tmp/rpm-tmp.xfk6P4 (%build)
Child return code was: 1
EXCEPTION: [Error()]
Traceback (most recent call last):
  File "/usr/lib/python3.7/site-packages/mockbuild/trace_decorator.py", line 96, in trace
    result = func(*args, **kw)
  File "/usr/lib/python3.7/site-packages/mockbuild/util.py", line 636, in do
    raise exception.Error("Command failed: \n # %s\n%s" % (command, output), child.returncode)
mockbuild.exception.Error: Command failed: 
 # bash --login -c /usr/bin/rpmbuild -bb --target riscv64 --nodeps /builddir/build/SPECS/lz4-java.spec