Add ROCKSDB_JAVA_NO_COMPRESSION flag

Summary:
In some CI test environment, compression libraries can't be successfully built. It still helps to build RocksDB there. Provide such an option to skip to download and build compression libraries.
Closes https://github.com/facebook/rocksdb/pull/2135

Differential Revision: D4872617

Pulled By: siying

fbshipit-source-id: bb21ac373bc62a2528cdf1ca4547e05fcae86214

Makefile

@@ -1482,10 +1482,14 @@ liblz4.a:
 java_static_libobjects = $(patsubst %,jls/%,$(LIBOBJECTS))
 CLEAN_FILES += jls
 
+ifneq ($(ROCKSDB_JAVA_NO_COMPRESSION), 1)
+JAVA_COMPRESSIONS = libz.a libbz2.a libsnappy.a liblz4.a
+endif
+
 JAVA_STATIC_FLAGS = -DZLIB -DBZIP2 -DSNAPPY -DLZ4
 JAVA_STATIC_INCLUDES = -I./zlib-$(ZLIB_VER) -I./bzip2-$(BZIP2_VER) -I./snappy-$(SNAPPY_VER) -I./lz4-$(LZ4_VER)/lib
 
-$(java_static_libobjects): jls/%.o: %.cc libz.a libbz2.a libsnappy.a liblz4.a
+$(java_static_libobjects): jls/%.o: %.cc $(JAVA_COMPRESSIONS)
 	$(AM_V_CC)mkdir -p $(@D) && $(CXX) $(CXXFLAGS) $(JAVA_STATIC_FLAGS) $(JAVA_STATIC_INCLUDES) -fPIC -c $< -o $@ $(COVERAGEFLAGS)
 
 rocksdbjavastatic: $(java_static_libobjects)
@@ -1494,7 +1498,7 @@ rocksdbjavastatic: $(java_static_libobjects)
 	$(CXX) $(CXXFLAGS) -I./java/. $(JAVA_INCLUDE) -shared -fPIC \
 	  -o ./java/target/$(ROCKSDBJNILIB) $(JNI_NATIVE_SOURCES) \
 	  $(java_static_libobjects) $(COVERAGEFLAGS) \
-	  libz.a libbz2.a libsnappy.a liblz4.a $(JAVA_STATIC_LDFLAGS)
+	  $(JAVA_COMPRESSIONS) $(JAVA_STATIC_LDFLAGS)
 	cd java/target;strip -S -x $(ROCKSDBJNILIB)
 	cd java;jar -cf target/$(ROCKSDB_JAR) HISTORY*.md
 	cd java/target;jar -uf $(ROCKSDB_JAR) $(ROCKSDBJNILIB)