Re-enable build of usrp FX2 firmware

Back in df354005f3, for some reason
building the USRP1 FX2 firmware was disabled.  Let's re-enable it, as
the FX2 firmware is required as an essential part of USRP1 device
operation.  It's loaded into the FX2 RAM over USB after the initial USB
attach.

As the firmware code has meanwhile been ported to a more modern
SDCC dialect (SDCC 3.2 or later, released in 2012), we have to adjust
the required minimum SDCC version.

Change-Id: I66ecc66bca3e8c171d2dd0d15c71186e16e8cc3b

configure.ac

@@ -74,6 +74,8 @@ AM_CONDITIONAL(HAVE_DOXYGEN, test $DOXYGEN != false && test "x$doxygen" = "xyes"
 AC_CHECK_PROG([XMLTO],[xmlto],[yes],[])
 AM_CONDITIONAL([HAS_XMLTO], [test x$XMLTO = xyes])
 
+USRP_SDCC([3.2.0],[],[passed=no;AC_MSG_RESULT([Unable to find firmware compiler SDCC 3.x.])])
+
 AC_CONFIG_FILES([
   Makefile
   usrp.pc
@@ -92,6 +94,10 @@ AC_CONFIG_FILES([
   host/apps/Makefile
   firmware/Makefile
   firmware/include/Makefile
+  firmware/lib/Makefile
+  firmware/src/Makefile
+  firmware/src/common/Makefile
+  firmware/src/usrp2/Makefile
   fpga/Makefile
   fpga/rbf/Makefile
   fpga/rbf/rev2/Makefile

firmware/Makefile.am

@@ -19,5 +19,4 @@
 # Boston, MA 02110-1301, USA.
 # 
 
-SUBDIRS = include
-# compilation broken: SUBDIR += lib src
+SUBDIRS = include lib src

m4/usrp_sdcc.m4

@@ -21,7 +21,7 @@ AC_DEFUN([USRP_SDCC],
 [
 	sdccok=yes
 	AC_CHECK_PROG(XCC, sdcc, sdcc -mmcs51 --no-xinit-opt,no)
-	AC_CHECK_PROG(XAS, asx8051, asx8051 -plosgff,no)
+	AC_CHECK_PROG(XAS, sdas8051, sdas8051 -plosgff,no)
 
 	if test "$XCC" = "no" -o "$XAS" = "no" ; then
 		AC_MSG_RESULT([USRP requires sdcc version 2. sdcc not found. See http://sdcc.sf.net])