Remove unused conditionals

The conditionals that used those values were removed from
bindings/Makefile.am with commit b0408037 which replaced code
that installed the Perl bindings in different locations
depending on the OS with code that installed in all locations.

configure.ac

@@ -829,11 +829,6 @@ AS_IF([test x"${cf_with_usrp}" = "xyes"],[
 
 AM_CONDITIONAL([HAVE_USRP], [test x"${cf_with_usrp}" = "xyes"])
 
-AM_CONDITIONAL(BUILD_OS_IS_UBUNTU, [test x"$build_os" = ubuntu])
-AM_CONDITIONAL(BUILD_OS_IS_FEDORA, [test x"$build_os" = fedora])
-echo Build_OS is $build_os
-
-
 
 ## -------------------------------- ##
 ## Prepare rig backend dependencies ##