[SPARK-2358][MLLIB] Add an option to include native BLAS/LAPACK loader in the build

It would be easy for users to include the netlib-java jniloader in the spark jar, which is LGPL-licensed. We can follow the same approach as ganglia support in Spark, which could be enabled by turning on "-Pganglia-lgpl" at build time. We can use "-Pnetlib-lgpl" flag for this.

Author: Xiangrui Meng <meng@databricks.com>

Closes #1295 from mengxr/netlib-lgpl and squashes the following commits:

aebf001 [Xiangrui Meng] add a profile to optionally include native BLAS/LAPACK loader in mllib

mllib/pom.xml

@@ -78,6 +78,19 @@
       <scope>test</scope>
     </dependency>
   </dependencies>
+  <profiles>
+    <profile>
+      <id>netlib-lgpl</id>
+      <dependencies>
+        <dependency>
+          <groupId>com.github.fommil.netlib</groupId>
+          <artifactId>all</artifactId>
+          <version>1.1.2</version>
+          <type>pom</type>
+        </dependency>
+      </dependencies>
+    </profile>
+  </profiles>
   <build>
     <outputDirectory>target/scala-${scala.binary.version}/classes</outputDirectory>
     <testOutputDirectory>target/scala-${scala.binary.version}/test-classes</testOutputDirectory>