Increase heap size for jgit tests

Otherwise PackFileTest.testDelta_LargeObjectChain() reproducibly
fails with OutOfMemoryError on Mac OS X 10.6.4.

Change-Id: I6a55ff9ba181102606a0d99ffd52392a1615a422
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.test/org.eclipse.jgit.core--All-Tests (Java 6).launch

@@ -18,4 +18,5 @@
 <stringAttribute key="org.eclipse.jdt.launching.JRE_CONTAINER" value="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6"/>
 <stringAttribute key="org.eclipse.jdt.launching.MAIN_TYPE" value=""/>
 <stringAttribute key="org.eclipse.jdt.launching.PROJECT_ATTR" value="org.eclipse.jgit.test"/>
+<stringAttribute key="org.eclipse.jdt.launching.VM_ARGUMENTS" value="-Xmx256m"/>
 </launchConfiguration>

org.eclipse.jgit.test/pom.xml

@@ -126,7 +126,7 @@
         <artifactId>maven-surefire-plugin</artifactId>
         <version>2.4.2</version>
         <configuration>
-          <argLine>-Dfile.encoding=UTF-8</argLine>
+          <argLine>-Xmx256m -Dfile.encoding=UTF-8</argLine>
           <includes>
             <include>**/*Test.java</include>
             <include>**/*TestCase.java</include>