Fixed build for x86_64-linux-android that doesn't support PCLMUL (#429)

librocksdb-sys/build.rs

@@ -103,13 +103,16 @@ fn build_rocksdb() {
         // This is needed to enable hardware CRC32C. Technically, SSE 4.2 is
         // only available since Intel Nehalem (about 2010) and AMD Bulldozer
         // (about 2011).
-        config.define("HAVE_PCLMUL", Some("1"));
         config.define("HAVE_SSE42", Some("1"));
         config.flag_if_supported("-msse2");
         config.flag_if_supported("-msse4.1");
         config.flag_if_supported("-msse4.2");
+
+        if !target.contains("android") {
+            config.define("HAVE_PCLMUL", Some("1"));
             config.flag_if_supported("-mpclmul");
         }
+    }
 
     if target.contains("darwin") {
         config.define("OS_MACOSX", Some("1"));