Make features optional.

Signed-off-by: Greg Watson <g.watson@computer.org>
diff --git a/org.eclipse.ptp.product-feature/feature.xml b/org.eclipse.ptp.product-feature/feature.xml
index dc3aaba..ace52ae 100644
--- a/org.eclipse.ptp.product-feature/feature.xml
+++ b/org.eclipse.ptp.product-feature/feature.xml
@@ -72,43 +72,63 @@
 
    <includes
          id="org.eclipse.linuxtools.cdt.libhover.feature"
-         version="0.0.0"/>
+         version="0.0.0"
+         optional="true"
+         search-location="both"/>
 
    <includes
          id="org.eclipse.linuxtools.changelog.c"
-         version="0.0.0"/>
+         version="0.0.0"
+         optional="true"
+         search-location="both"/>
 
    <includes
          id="org.eclipse.linuxtools.gprof.feature"
-         version="0.0.0"/>
+         version="0.0.0"
+         optional="true"
+         search-location="both"/>
 
    <includes
          id="org.eclipse.linuxtools.oprofile.feature"
-         version="0.0.0"/>
+         version="0.0.0"
+         optional="true"
+         search-location="both"/>
 
    <includes
          id="org.eclipse.linuxtools.rpm"
-         version="0.0.0"/>
+         version="0.0.0"
+         optional="true"
+         search-location="both"/>
 
    <includes
          id="org.eclipse.linuxtools.systemtap"
-         version="0.0.0"/>
+         version="0.0.0"
+         optional="true"
+         search-location="both"/>
 
    <includes
          id="org.eclipse.linuxtools.callgraph.feature"
-         version="0.0.0"/>
+         version="0.0.0"
+         optional="true"
+         search-location="both"/>
 
    <includes
          id="org.eclipse.linuxtools.valgrind"
-         version="0.0.0"/>
+         version="0.0.0"
+         optional="true"
+         search-location="both"/>
 
    <includes
          id="org.eclipse.linuxtools.gcov"
-         version="0.0.0"/>
+         version="0.0.0"
+         optional="true"
+         search-location="both"/>
 
    <includes
          id="org.eclipse.linuxtools.lttng2.control"
-         version="0.0.0"/>
+         version="0.0.0"
+         optional="true"
+         search-location="both"/>
 
    <includes
          id="org.eclipse.photran"