Fix jni library name for PowerPC Architecture

Summary:
Right now, building rocksdbjava in PowerPC is broken due to JNI library name. I figured it out that "uname -m" and java's os.arch matches in PowerPC architecture. I made use of this advantage to fix the issue. More info can found from this issue  --> https://github.com/facebook/rocksdb/issues/1317
Closes https://github.com/facebook/rocksdb/pull/2040

Differential Revision: D4779967

Pulled By: siying

fbshipit-source-id: 259f939

Makefile

@@ -1380,7 +1380,12 @@ ifeq ($(PLATFORM), OS_SOLARIS)
 else
 	ARCH := $(shell getconf LONG_BIT)
 endif
+
+ifeq (,$(findstring ppc,$(MACHINE)))
         ROCKSDBJNILIB = librocksdbjni-linux$(ARCH).so
+else
+        ROCKSDBJNILIB = librocksdbjni-linux-$(MACHINE).so
+endif
 ROCKSDB_JAR = rocksdbjni-$(ROCKSDB_MAJOR).$(ROCKSDB_MINOR).$(ROCKSDB_PATCH)-linux$(ARCH).jar
 ROCKSDB_JAR_ALL = rocksdbjni-$(ROCKSDB_MAJOR).$(ROCKSDB_MINOR).$(ROCKSDB_PATCH).jar
 ROCKSDB_JAVADOCS_JAR = rocksdbjni-$(ROCKSDB_MAJOR).$(ROCKSDB_MINOR).$(ROCKSDB_PATCH)-javadoc.jar

java/src/main/java/org/rocksdb/util/Environment.java

@@ -42,7 +42,7 @@ public class Environment {
     if (isUnix()) {
       final String arch = is64Bit() ? "64" : "32";
       if(isPowerPC()) {
-        return String.format("%sjni-linux-ppc%s", name, arch);
+        return String.format("%sjni-linux-%s", name, ARCH);
       } else {
         return String.format("%sjni-linux%s", name, arch);
       }