bitbake: allow fakeroot functionality to be provided by an alternative program

If the variable FAKEROOT is set its value will be used, otherwise we default
to fakeroot.

Signed-off-by: Joshua Lock <josh@linux.intel.com>

bitbake/lib/bb/build.py

@@ -253,7 +253,7 @@ def exec_func_shell(func, d, runfile, logfile, flags):
 
     # execute function
     if flags['fakeroot']:
-        maybe_fakeroot = "PATH=\"%s\" fakeroot " % bb.data.getVar("PATH", d, 1)
+        maybe_fakeroot = "PATH=\"%s\" %s " % (bb.data.getVar("PATH", d, 1), bb.data.getVar("FAKEROOT", d, 1) or "fakeroot")
     else:
         maybe_fakeroot = ''
     lang_environment = "LC_ALL=C "