Revert "Removed usrp2-firmware from being automatically built."

This reverts commit 3bb029afe0d7de1bd4aadaecf4eb7121e0f2c84d.

The change reverted removed the usrp2/firmware from the distribution
tarballs and also had configure report that it was building the usrp2
firmware when in fact it wasn't.

What is the problem that you are trying to solve?

Example of configure output that lies:

    config.status: creating config/Makefile
    config.status: creating config.h
    config.status: executing depfiles commands

    *********************************************************************
    The following GNU Radio components have been successfully configured:

    usrp2-firmware

    You my now run the make command to build these components.

    *********************************************************************
    The following GNU Radio components have been successfully configured:

    config
    gruel
    gnuradio-core
    usrp
    usrp2

    [snip]

1 files changed, 3 insertions, 0 deletions

diff --git a/bootstrap b/bootstrap
index 7daff90d1..463ff165b 100755
--- a/bootstrap
+++ b/bootstrap
@@ -28,3 +28,6 @@ autoheader
 libtoolize --automake
 automake --add-missing -Wno-portability -Wno-override -Wnone
 #automake --add-missing -Wno-portability
+
+# Run bootstrap in any subprojects
+(cd usrp2/firmware ; ./bootstrap)