bitbake: main: Remove unneeded float()

There is already a type=float, so the float() is not needed, which also makes
the error clearer:

$ export BB_SERVER_TIMEOUT=10000AA
With float():
$ bitbake quilt-native
[snip]
ValueError: could not convert string to float: '10000AA'

Without float():
$ bitbake quilt-native
[snip]
optparse.OptionValueError: option --idle-timeout: invalid floating-point value: '10000AA'

The second one tells clearly where is wrong.

(Bitbake rev: 7a4ea1e6a10f20d80009a78f4f0aebf8f90095fd)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/main.py

@@ -259,7 +259,7 @@ class BitBakeConfigParameters(cookerdata.ConfigParameters):
                           help="The name/address for the bitbake xmlrpc server to bind to.")
 
         parser.add_option("-T", "--idle-timeout", type=float, dest="server_timeout",
-                          default=float(os.environ.get("BB_SERVER_TIMEOUT", 0)) or None,
+                          default=os.environ.get("BB_SERVER_TIMEOUT", 0) or None,
                           help="Set timeout to unload bitbake server due to inactivity")
 
         parser.add_option("", "--no-setscene", action="store_true",