Fix enum flag with Python 3

Using Python 3.5 (I assume it's the same with 3.4 and lower, but I didn't
test), I see this:

  print (enum flag_enum) (FLAG_1)^M
  Python Exception <class 'TypeError'> %x format: an integer is required, not gdb.Value: ^M
  $7 = ^M
  (gdb) FAIL: gdb.python/py-pp-maint.exp: print FLAG_1

Apparently, this idiom, where v is a gdb.Value, was possible with Python 2,
but not with Python 3:

  '%x' % v

In Python 2, it would automatically get converted to an integer.  To solve
it, I simply added wrapped v in a call to int().

  '%x' % int(v)

In Python 2, the int type is implemented with a "long" in C, so on x86-32 it's
32-bits.  I was worried that doing int(v) would truncate the value and give
wrong results for enum values > 32-bits.  However, the int type != the int
function.  The int function does the right thing, selecting the right integer
type for the given value.  I tested with large enum values on x86-32 and
Python 2, and everything works as expected.

gdb/ChangeLog:

	* python/lib/gdb/printing.py (_EnumInstance.to_string): Explicitly
	convert gdb.Value to integer type using int().

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2016-01-19  Simon Marchi  <simon.marchi@polymtl.ca>
+
+	* python/lib/gdb/printing.py (_EnumInstance.to_string): Explicitly
+	convert gdb.Value to integer type using int().
+
 2016-01-19  John Baldwin  <jhb@FreeBSD.org>
 
 	* configure.ac: Include <sys/types.h when checking for "r_fs" in

gdb/python/lib/gdb/printing.py

@@ -239,7 +239,7 @@ class _EnumInstance:
         if not any_found or v != 0:
             # Leftover value.
             flag_list.append('<unknown: 0x%x>' % v)
-        return "0x%x [%s]" % (self.val, " | ".join(flag_list))
+        return "0x%x [%s]" % (int(self.val), " | ".join(flag_list))
 
 class FlagEnumerationPrinter(PrettyPrinter):
     """A pretty-printer which can be used to print a flag-style enumeration.