Add pigz repository

* pigz is an optimized gzip which uses multiple cores
 * We're using pigz for compressed Nandroid support in recovery

Change-Id: I87c5d2f9b67e7104c75460279eb640fdfa99d9b7

default.xml

@@ -186,6 +186,7 @@
   <project path="external/openssl" name="CyanogenMod/android_external_openssl" groups="pdk" />
   <project path="external/openvpn" name="CyanogenMod/android_external_openvpn" />
   <project path="external/oprofile" name="CyanogenMod/android_external_oprofile" />
+  <project path="external/pigz" name="CyanogenMod/android_external_pigz" />
   <project path="external/ping" name="CyanogenMod/android_external_ping" />
   <project path="external/ping6" name="CyanogenMod/android_external_ping6" />
   <project path="external/powertop" name="CyanogenMod/android_external_powertop" />