[python] migrate 2.7 to 3

Summary:
Used `2to3` but had to (poorly, sorry!) fix byte -> string output of processes.

update-submodule: facebook-clang-plugins

Reviewed By: ngorogiannis

Differential Revision: D20672767

fbshipit-source-id: 852c7e973

INSTALL.md

@@ -15,7 +15,6 @@ Here are the prerequisites to be able to compile Infer on MacOSX. This
 is required to compile everything from source.
 
 - opam >= 2.0.0 (instructions [here](https://opam.ocaml.org/doc/Install.html#OSX))
-- Python 2.7
 - sqlite
 - pkg-config
 - Java (only needed for the Java analysis)
@@ -42,7 +41,6 @@ Here are the prerequisites to be able to compile Infer on Linux. This
 is required to compile everything from source.
 
 - opam >= 2.0.0
-- Python 2.7
 - pkg-config
 - Java (only needed for the Java analysis)
 - gcc >= 5.X or clang >= 3.4 (only needed for the C/Objective-C analysis)

configure.ac

@@ -137,9 +137,6 @@ AS_IF([test "x$enable_c_analyzers" = "xyes"], [
 ])
 # end if($enable_c_analyzers)
 
-AC_CHECK_TOOL([PYTHON27], [python2.7], [no])
-AC_ASSERT_PROG([python2.7], [$PYTHON27])
-
 AC_CHECK_TOOL([XCODE_SELECT], [xcode-select], [no])
 AS_IF([test "x$XCODE_SELECT" != "xno"], [XCODE_SELECT_OUT=`xcode-select -p`])
 

facebook-clang-plugins

@@ -1 +1 @@
-Subproject commit bab39197465689e39b2462f052d2895fe13c1a60
+Subproject commit 48d27425e9e9e8d0bace06e9e7893cb23b21a2a4

infer/tests/testlock.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2.7
+#!/usr/bin/env python3
 
 # Copyright (c) Facebook, Inc. and its affiliates.
 #