meta/scripts: python3: rename file -> open

file() API doesn't exist in python 3, convert to open(). Also handle
some cases where files aren't closed. Compatible with python 2.7.

[Contributions from Ed and Richard]

(From OE-Core rev: 0f4ec13e11bb8abe21aba2a28547dfb9372bc377)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/apt/apt-native.inc

@@ -18,7 +18,7 @@ python do_install () {
 
 python do_install_config () {
     indir = os.path.dirname(d.getVar('FILE',1))
-    infile = file(oe.path.join(indir, 'files', 'apt.conf'), 'r')
+    infile = open(oe.path.join(indir, 'files', 'apt.conf'), 'r')
     data = infile.read()
     infile.close()
 
@@ -30,7 +30,7 @@ python do_install_config () {
 
     outpath = oe.path.join(outdir, 'apt.conf.sample')
     if not os.path.exists(outpath):
-        outfile = file(outpath, 'w')
+        outfile = open(outpath, 'w')
         outfile.write(data)
         outfile.close()
 }